9th Class Chemistry English Medium Chapter 1 Online Short Question Preparations

Why fluorine is more non-metallic than chlorine ?

• Ans 1:
  Fluorine is more reactive than chlorine because the electronegativity of fluorine is greater tahn chlorine
  
  

Why does atomic size increases in a group ?

• Ans 1: The size of atoms or their radii increases from top to bottom in a group . It is because a new shell of electrons is added up the successive period . Which the effect of nuclear charge

Write two examples of gas into gas solution .

• Ans 1: 1:Air
  
• Ans 2: 2: Mixture of H₂ and He in wheather ballons
• Ans 3: 3: Mixture of N2 and O2 in clinders for respiration

What is the valency id following ?

(A) Barium (B) Nitrogen (C) Sodium (D) Sulphur

• Ans 1: Elements valency
  1: Barium 2
  2: Nitrogen 3
  3: Sodium 1
  4: Sulphur 2

Define chemistry ? Explain two branches of chemistry .

• Ans 1: Chemistry : The Branch of science which deals with the composition , structure, properties and reaction of matter is called chemistry
• Ans 2: Branches of chemistry
  
  
• Ans 3: Physical chemistry : Physical chemistry is defined as the relationship between the composition and physical properties of matter , along with the changes in them
• Ans 4: Nuclear chemistry : It is the branch of chemistry that deals with the radioactivity , nuclear processes and their properties

Write chemical reaction that takes place during working of Nelson's cell.

• Ans 1: Following reactions take place in Nelson's cell
  Ions formed in Brine
  
  2NaCl _(aq)➜ 2Na⁺ _(aq) +2Cl_(aq)
• Ans 2: Oxidation at anode :
  2Cl _(aq)➜ Cl2 _(g) + 2e^-
• Ans 3: Reduction at cathode :
  2H₂O₍₁₎ + 2e➜ H2 _(g) +2OH_(aq)
  _{2Na+ (aq) + 2OH (aq)}➜ 2NaOH _(aq)
• Ans 4: Complete reaction :
  2NaCl _(aq) + 2H₂O➜ H2 (g) + Cl_{2 (g)} + 2NaOH _(aq)

Write four physical properties of calcium metals .

• Ans 1: 1: Calcium is silvery grey and fairly harder metal
• Ans 2: 2:Good conductor of heat and electricity
• Ans 3: 3: Melting point of 839°C
• Ans 4: 4: Flame colour of calcium metal is brick red

Define single covalent bond and give one example .

• Ans 1: 'When one electron is contributed by each bonded atom ,one bond pair is formed and it forms a single covalent bond '
• Ans 2: Representation of a single covalent bond :
  While drawing the structure of molecules having single covalent bond . A line (_) is drawn between those atoms which share a single bond pair
• Ans 3: For example : Molecules of H₂ .Cl₂ . HCL and CH₄ are examples of single covalent bond

Write down the name of any two elements which were discovered in early ages .

• Ans 1: Following elements were discovered in early ages
• Ans 2: 1: Crbon
• Ans 3: 2: Gold
• Ans 4: 3: Silver
• Ans 5: 4: Copper

Define unsaturated solution .

• Ans 1: The solution which have capacity to dissolve more amount of solute is called unsaturated solution

A patient has goiter . How will it be detected ?

• Ans 1: The radioactivity isotopes are used as tracers in medicine to diagnose the presence of tumor in human body . Isotope of I-131 is used for diagnose of goiter in thyroid gland

For what purpose , Iodine-131 is used ?

• Ans 1: Isotopes of iodine I-131 is used to diagnose goiter in thyroid

Define transition element ?

• Ans 1: _{d block elements called transition element}

Write any two applications of inorganic chemistry.

• Ans 1: Inorganic chemistry has applications in following aspects of the chemistry industry
• Ans 2: 1: Glass industry
• Ans 3: 2: Cement industry
• Ans 4: 3: Ceram[ics and metallurgy

Can pure gold be used for making ornaments?If not why?

• Ans 1:
  No. pure gold cannot be used for making ornaments.
  because gold is too sift to be used as such It is always alloyed with copper. silver and some other metals
  
  

What happens at cathode in galvanic cell ?

• Ans 1: Reduction process takes place at cathode in galvanic cell
  Cu⁺² + 2e➜ Cu

Can liquid and gases be brittle?

• Ans 1: No, Only solid non-metals are brittle.

Which force drives the non-spontaneous reaction to take place ?

• Ans 1: Non-spontaneous reactions are those which take place in the presence of an external agent . These reactions takes place in galvanic and electrolytic cells
• Ans 2:
  

Name a metal which exists in liquid form? Ans: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state

• Ans 1: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state

Write down chemical formula of calcium phosphate and sodium chloride ..

• Ans 1: Chemical formula of calcium phosphate and sodium chloride is as fellows :
• Ans 2: 1: Calcium phosphate Ca3 (PO4)2
• Ans 3: 2: Sodium chlorideNaCl

What is meant by colloid ?

• Ans 1: The solutions in which the solute particles are larger than those solute particles present in true solution but not large enough to be seen with naked eye are called colloid solution . They show tyndal effect
• Ans 2: Example : Milk , ink , jelly , toothpaste etc

Anode of downs cell is made up of non metal , what is its name ?

• Ans 1: Anode of down cell is made of non-metal , Its name is graphite . The Cl^- ions are oxidized to give Cl₂ gas at anode

Define Industrial Chemistry and Analytical Chemistry.

• Ans 1: Industrial Chemistry: "This branch of chemistry is related to the the industrial processes" It is associated with studies of properties uses and application of techniques for the preparation of industrial sales on large scale.
• Ans 2: Analytical Chemistry:It deals with the detection and estimation of elements and compounds. In this the composition of elements is primarily analysed."

Define electrolyte . Give an example .

• Ans 1: Electrolyte : The substance which can conduct electricity in their solution or molten states are called electrolytes . Salts and acids are good electrolytes
• Ans 2: Example : NaCl , NaOH , H₂SO₄

Differentiate between Lone pair and bond pair of electrons .

• Ans 1: Long pair : The pair of electrons which remain unshared during covalent bond formation is called long pair
• Ans 2: Bond pair : Shared pair of electrons in the covalent bond called bond pair

Define triads and law of octaves .

• Ans 1: Triads : The group of three elements called triads . In these groups central and middle element had atomic mass average of the other two element
• Ans 2: Law of octaves : Newlands notices that there was a repetition in chemical properties of every eight element if they were arranged by their increasing atomic number

Which metals are the most malleable and ductile ?

• Ans 1: Gold (Au) is the most malleable and ductile of all metals . One gram of gold can be drawn into a wire of one and called ductile

What are non - electrolytes .Give one example

• Ans 1: The substances , which do not ionize in their aqueous solutions and do not allow the current to pass through their solutions are called non-electrolytes
• Ans 2: For example : sugar solution and benzene are non - electrolytes

How metallic character is changes in a group of periodic table ?

• Ans 1: Metallic character increase in a group from top to bottom due to increase in the size of atoms
• Ans 2: For example : potassium is more electropositive than sodium

Define Crystalline solids and give two examples .

• Ans 1: Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solids
• Ans 2: Example : Diamonds , NaCl etc

Differentiate between molecule or molecular ion ?

• Ans 1: Molecule :
  1: It is the smallest particle of a compound which can exist independently and shows all the properties of that compound

  2: It is always neutral

  3: It is formed by the combination of atoms

  4: It is a stable unit
• Ans 2: Molecular ion :
  1:It is formed by gain or loss of electrons by a molecule

  2: It can have negative or positive charge
  3: It is formed by the ionization of molecule
  4: It is a reactive specie

Differentiate between empirical and molecular formula.

• Ans 1: Empirical formula: it is the simplest whole number ratio of atoms present in a compound
  e.g. Empirical formula of benzene is CH.
• Ans 2: Molecular formula: It shows the actual number of atoms of each element present in a molecule of that compound.
  e.g.
  Molecular formula of benzene is C₆H₆

Describe atIeast two necessary conditions for the formation of a covalent bond.

• Ans 1: Iwo necessary conditions for the formation of covalent bond are: (.) The electronegativity difference between atoms must be less. So. that the shared pair of electrons is attracted by both the atoms equally. (i1) Maximum 3 to 6 electrons are present in their valence shells

Give the reaction of mangnesium with O2 And N2 .

• Ans 1:
  Reaction of magnesium with O2 :
  They are less reactive towards oxygen and oxides are formed on heating
  2Mg + ➜ 2MgO
• Ans 2:
  Rection with magnesium with N2 :
  They form stable Nitrides when heated with :
  3Mg + N2 ➜ Mg2N2

Is atomic mass unit a SI unit of an atomic mass?

• Ans 1: Yes , Atomic mass unit is SI unit of atomic mass.

Write two uses of redox reaction .

• Ans 1: Redox reaction are useful in batteries to produce energy and this electricity is used to drive non-spontaneous reaction

What is a triple covalent bond, explain with an example?

• Ans 1: Ans: When each bonded atom contributes three electrons, three bond pairs are involved in bond formation. This type is called triple covalent bond. Three small lines are used to indicate these three pairs of electrons between those atoms in the molecules of such compounds. For example: Nt & C2H2 Formulas: N.N.H-C==C-H

What are electrolytic cell ?

• Ans 1: Electrolytic cell : The type of electrochemical cell in which the non-spontaneous chemical reaction is carried out with the help of electric current is called electrolytic cell
• Ans 2: Example : Down's cell, Nelson's cell

Write uses of magnesium .

• Ans 1: 1: Magnesium is used in flash light bulbs and in fireworks .
• Ans 2: 2: It is used in the manufacturing of light alloys
• Ans 3: 3: Magnesium ribbon is used in thermic process to ignite aluminium
• Ans 4: 4: Magnesium is used as anode for prevention of corrosion

How can you differentiate between organic and inorganic chemistry .

• Ans 1: Organic chemistry : It is the study of the properties and behavior of hydrocarbons (compounds of carbon and hydrogen ) and their derivatives
• Ans 2: Inorganic chemistry : It is the study of the properties and behavior of all elements except the hydrocarbons and their derivatives

Why is gold used to make jewelry?

• Ans 1: Gold is very nonreactive or inert metal. It is not affected by atmosphere. It is not affected by any single mineral acid or base. It is most malleable and ductile of all the metals. Due these reasons the gold is used to make jewelry.

An element with A = 39 , Z = 19 .Calculate the number of electrons and protons in one atom of this element

• Ans 1: Atomic mass of an element = A = 39
  Atomic number of element = Z = 19
  As we know that atomic number is the number of protons present in the nucleus of an atom so , proton and electron always equal in any atom , that's why ,
  Number of protons =19
  Number of electrons = 19

Define reduction on the basis of electron and give example .

• Ans 1: Reduction reaction : The gain of electrons by atom or ion is called reduction reaction .
• Ans 2: Example : Cl_(g) + le^-➜ Cl^- _(g)
• Ans 3: In above reaction , a chlorine atom is changed into a chlorine ion through reduction . Hence it is approved that conversion of an atom into ion is a reduction reaction

Which force drives the non-spontaneous reaction to take place ?

• Ans 1: Non-spontaneous reactions are those which take place in the presence of an external agent . These reactions takes place in galvanic and electrolytic cells
• Ans 2:
  

Write four physical properties of metals

• Ans 1: 1: Almost all metals are solid (Except mercury)
• Ans 2: 2: They have high melting and boiling points (except alkalimetals )
• Ans 3: 3: They possess ,metallic lusture and can be polished
• Ans 4: 4: They are good conductor of heat and electricity

What is mean by cation and anion? Explain with example.

• Ans 1: Cation:
  The cations are formed when an atom loses electrons from its outmost shells. For example cations are Na⁺ , K⁺, Ca⁺²
  Na ______> Na⁺ + 1e^-
• Ans 2: Anions:
  The anions are formed when an atom gains or addition of electrons to an atom Examples of anions are C^-l , O^-2
  Cl + 1e^- _______> Cl^-1

Why 2nd ionization energy of an elements is higher than first one?

• Ans 1: fins: energy required to remove an electron from isolated mono positive gaseous ion (M') is called second ionization energy. So more energy is required to remove second electron from a mono positive gaseous ion because there is more electrostatic force present between the nuclei and electron. M⁺➜M⁺²1e^-

Calculate the oxidation number of nitrogen in HNO₃ .

• Ans 1: HNO_{3 = (1) +(N) +3 (-2)}
  _{= 1+N-6}
  _{N = +5}

Write electronic configuration of Chloride ion Cl^-

• Ans 1: Electronic configuration of Chloride ion
• Ans 2: Cl = 1s² , 2s² , 2p⁶ , 3s² , 3p⁴

What is matter ?

• Ans 1: Anything which has mass and occupy space is called matter

Why and how are element arranged in 4th period ?

• Ans 1: Elements are arranged in 4th period according to increasing atomic number . The 4th period contains 18 elements beginning with potassium and ending with krypton . As a rule . 4th period elements fill their 4th subshells in that order however there are exception such as chromium

Why is vapour pressure higher at high temperature?

• Ans 1: At high temperature, vapour pressure is higher than at low temperature. At elevated temperature, the Kinetic energy of the molecules increases enough to enable them to vaporize and exert pressure.

Write electronic configuration of Aluminuim .

• Ans 1: Atomic number of Aluminium is 13
  ₁₃Al = 1s² , 2s², 2p⁶, 3s², 3p¹

Give the non-metallic trend in halogens .

• Ans 1:
  Elements of group of periodic table consists of fluorine ,chlorine, bromine , iodine . and astatine
  Their non-metallic nature decrease down the group . Fuorine is most metallic ,while iodine is least non-metallic
  
  

What is atomic number, how it is represented?

• Ans 1: "The atomic number of an element is equal to the number of protons present in the nucleus of its atoms." Representation:It is represented by "Z"

Write down the electronic configuration of fluorine and Neon

• Ans 1: Electronic configuration of fluorine:
  ₉F=1s² , 2s² , 2p⁴
• Ans 2: Electronic configuration of Neon :
  ₁₀Ne = 1s² , 2s² , 2p⁶

How galvanizing of iron sheets is done ?

• Ans 1: The process of Galvanizing is carried out by dipping a clean iron sheet in a zinc chloride bath and then heating it . After this iron sheet is removed , rolled into molten zinc metal bath and finally air -cooled . Advantages of galvanizing is that zinc protects the iron against corrosion

How much amount of KOH required to form 1 molar solution ?

• Ans 1: Concentration of solution = 1dm³
  Molar mass of KOH = 39+16+1
  = 56 mol
• Ans 2: Mass x Molarity x Molar mass x amount of solution
  =1 x 56 x 1 = 56
• Ans 3: 56g KOH required to form 1 molar solution

What is atomic number of Sulphur ? Write down its electronic configuration .

• Ans 1: Atomic number of Sulphur IS 16 .
• Ans 2: S = 1s² , 2s² , 2p⁶ , 3s² , 3p⁴

Define diatomic molecule and give example .

• Ans 1: If a molecule consists of two atoms called diatomic molecule
• Ans 2: For example : hydogen gas (H2) , Oxygen gas (O2) etc

How the properties of elements repeat after regular intervals?

• Ans 1: The modern periodic table is based upon the arrangement of elements according to increasing atomic number. When the elements are arranged according to increasing atomic number from left to right in a horizontal row. properties of elements were found repeating after regular intervals

Why Lanthanides an Actanides are placed separately below periodic table . Explain

• Ans 1: Because of space problem in periodic table two series of elements were placed separately below the normal periodic table to keep it in a manageable and presentable form . Since the two series start after Lanthanum (z=57) and Actinum (z=89) , so these two series of elements are named as Lanthanides and Actanides

Why is calcium more electropositive than magnesium ?

• Ans 1: Calcium is more electropositive than magnesium due to its large atomic size and less amount of ionization energy

In what conditions H2 reacts with l2 ? Give equation of the reaction .

• Ans 1:
  H2 reacts with l2 on heating and in the presence of catalyst to produce hydrogen iodide
  H2 + l2 ➜ 2Hl
  
  

How can you differentiate between organic and inorganic chemistry .

• Ans 1: Organic chemistry : It is the study of the properties and behavior of hydrocarbons (compounds of carbon and hydrogen ) and their derivatives
• Ans 2: Inorganic chemistry : It is the study of the properties and behavior of all elements except the hydrocarbons and their derivatives

Which factor controls the non-metallic character of the element?

• Ans 1: The non - metallic character of elements is depending upon the electron affinity and electron affinity and electronegativity

State three reasons why do you thing soft drink is a mixture and water is a compound .

• Ans 1: Soft drink is a mixture because :
  1: Its components are not bounded chemically
  2: The components do not have fix ratio
• Ans 2: 3: The components retain their physical and chemical properties
• Ans 3: Water is a compound because :
  1 : Its components namely hydrogen and oxygen are bounded chemically
  2: The components have fix ratio by mass
• Ans 4: 3: The components lose their chemical and physical properties

Write down chemical formula of calcium phosphate and sodium chloride ..

• Ans 1: Chemical formula of calcium phosphate and sodium chloride is as fellows :
• Ans 2: 1: Calcium phosphate Ca3 (PO4)2
• Ans 3: 2: Sodium chlorideNaCl

What is meant by true solution ?

• Ans 1: True solution are the homogeneous mixture of two or more than two components . Each components is mixed in such a way that their individual identity is not visible
• Ans 2: Example : Its simple example is a drop of solvent ink in water

What are shells ?

• Ans 1: Shells are specific energy levels around nucleus in which electron resolve
  e.g K,L,M,N

State three reasons why do you think air is a mixture and water a compound

• Ans 1: Air (mixture)
  1: Mixture is formed by the simple mixing up of the substances
  2: Air does not have a sharp and fixed melting point
  3: Air has heterogenous mixture composition
• Ans 2: Water (Compound) :
  1: It is formed by the chemical combination of atoms of elements
  2: Water has a sharp and fixed melting point
  3: Water has homogenous composition

Write down names of any two moderate reactive metals

• Ans 1: 1: Magnesium
• Ans 2: 2: Silver

What is the application of Inorganic Chemistry?

• Ans 1: It has application in every aspect of chemical industry such as glass, cement, ceramics and metallurgy.

How do atoms follow octet rule?

• Ans 1: Atoms follow octet rule to have the noble gas electronic configuration. For this purpose atoms attain 8 electrons in the outermost shell either by sharing. by losing or by gaining electrons

Define reduction .

• Ans 1: Reduction is defined as addition of hydrogen or removal of oxygen during a chemical reaction
• Ans 2: Addition of hydrogen :
• Ans 3: H₂S +Cl₂➜ S+2HCL
• Ans 4: Removal of oxygen : 2Zn + CO₂

What is galvanizing ?

• Ans 1: 1: The process of coating a thin layer of zinc on iron is called galvanizing
• Ans 2: 2: This process is carried out by dipping a clean iron sheet in a zinc chloride and then heating it . After this iron iron is removed , rolled into molten zinc metal bath and finally air cooled
• Ans 3: Advantages : Advantages of galvanizing is that zinc protects the iron against corrosion even after the coating surface is broken

Metals are good conductors of electricity .Why ?

• Ans 1: Metals have free moving electrons called mobile electrons . Due to presence of these electrons metals are good conductors of electricity

Name one solid, one liquid and one gaseous element present at room temperature?

• Ans 1: Solid : Sodium, Iron Liquid: Bromine and Mercury Gas: Oxygen , Nitrogen, and Chlorine

What elements do the following compound contains ?

• Ans 1: Sugar ,common salt , lime water and chalk
• Ans 2: Glucose :It contains carbon, hydrogen , and oxygen (C₆H₁₂O₆)
• Ans 3: Common salt : It contains sodium , and chlorine (NaCl)
• Ans 4: Lime water : It contains calcium ,oxygen , and hydrogen Ca (OH)₂
• Ans 5: Chalk : It contains calcium ,carbon, and oxygen CaCO₃

Differentiate between molecular mass and formula mas , which of the following is molecular formula ?

. H2O

.NaCl

.Kl

.H₂SO₄

• Ans 1: Molecular mass :
  The sum of atomic masses of all the atoms present in one molecule of a molecular compound is its molecular mass
  
  
• Ans 2: Formula : Molecular mass of water is 18 amu and that of carbon is 44 amu
• Ans 3: Formula mass :
  Formula mass is the sum of atomic masses of all the atoms present in one formula unit of a substance
• Ans 4: Example : Formula mass of sodium chloride is 85.5 amu and that of CaCO₃ is 100 amu
• Ans 5: H₂O Or H₂SO₄ are molecular formula

Why the size of atom does not decrease regularly in periods ?

• Ans 1: The atomic size does not decrease regularly in periods due to presence of transition elements . The size of atom first decreases then increases

Define redox reaction , Give an example .

• Ans 1: The reaction in which oxidation as well as reduction takes place at a time called redox reaction
• Ans 2: Example : Zn + CuSO₄➜ ZnSO₄ +Cu

How many times is 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams

• Ans 1: One mole of oxygen atom is 16 times heavier than the one mole of hydrogen

Give the electronic configuration of carbon atom.

• Ans 1: Atomic no. of carbon = Z= 6
  No of electrons in carbon atom =Z=6
  Electronic configuration of carbon atom=ls².2s²,2p²

How will you test whenever given solution is colloidal solution or not?

• Ans 1: If the panicles scatter the path of light rays thus emitting the beam of light i.e exhibit the Tyndall effect than the given solution is colloid.

In electroplating of chromium which salts is used as an electrolyte?

• Ans 1: In electroplating of chromium, Cr₂(SO₄)₃, is used as an electrolyte.

Why ionization energy of Na is less than Mg?

• Ans 1: Ionization energy of Na is less than Mg because Na requires less energy to lose its valence electron than magnesium. Ionization energy is that energy, which is required to remove outermost electrons from the gaseous state of an element.

Write electronic configuration of chlorine and carbon

• Ans 1: Electronic configuration of carbon : ¹² C ₆ = 1s² , 2s² , 2p²
• Ans 2: Electronic configuration of chlorine : ₁₇ Cl = 1S² , 2S², 2P⁶, 3S², 3P⁵

How meat can be preserved ?

• Ans 1: Table salt is the most important ingredient for curing meat and is used in large quantities . Salt kills and inhibits the growth of putrefying bacteria by drawing water out of the meat . Concentrations of salt up to 20% are required to kill most of the species of unwanted bacteria . Once properly salted , the meat contains enough salt to prevent the growth of many undesirable microbes

Is the Boyle's law applicable to liquid ? Give reason .

• Ans 1: No we can not apply Boyle's law to liquid because in them intermolecular distance is very less and they are highly incompressible so the effect of pressure does'nt effect much on liquids . That's why we can not apply Boyle's law to liquids

What are applications of inorganic chemistry?

• Ans 1: It has application in every aspect of chemical industry such as glass , cement , ceramics and metallurgy

What was the thickness of gild foil used in Rutherford's atomic model ?

• Ans 1: 0.00004 cm thick gold foil was used by Rutherford in his experiment
• Ans 2:
  

Which has more atoms :10g of Al or 10 g of Fe ?

• Ans 1: 10 g of A 1 has more atoms than 10 g of Fe
  For A 1
  
  
• Ans 2: Number of atoms = Mass/molar mass x N _A
  _{= 10/23 X 6.02 X 10}²³
  = 2.617X10²³
• Ans 3: For Fe :
  Number of atoms = Mass/molar mass x N _A
  = 10/56 X 6.02X10²³
  = 1.075 X 10²³
  
  

How atoms accommodate 8 electrons in their valence shells?

• Ans 1: toms can accommodate 8 electrons in their valence shell in three.
  1: By giving valence shell electrons
  2:By gaining valence shell electrons
  3:By sharing valence shell electrons with other atoms

Define Bond pair ?

• Ans 1: The valence electrons which take part in covalent bond is called bonding electrons . These electrons present in the incomplete valence shell

Define electrolytes and electro chemical cell .

• Ans 1: Electrolytes : The substances , which can conduct electricity in their aqueous solution or molten state , are called electrolytes
• Ans 2: For example : solution of salts , acids or bases are good electrolytes
• Ans 3: Electrochemical cell: Electrochemical cell is a system in which two electrons are dipped in the solution of an electrolyte which are connected to the battery . Electrochemical cell is an energy storage device in which either a chemical reaction takes place by using electric current or chemical reaction produces electric current

How can you justify that blood is a colloid?

• Ans 1:
  Blood appears to be a homogenous but actually it is a heterogeneous mixture. Blood particles do not settle down for a long time so we can say that blood is a colloidal solution
  n

Why elements are called s and p block elements ?

• Ans 1: Elements are called s and p block elementsbecause their last element is present in s and p sub shell

What is the nature of charge on cathode rays ?

• Ans 1: Their deflection in electric and magnetic field proves that they have negative charge

Why alkali metals are more reactive than alkaline earth metals ?

• Ans 1: Alkali metals are extremely reactive because of their ns¹valence shell electronic configuration . As there is only one electron in their valence shell , it can be easily given out . It is the reason that they are always found in in nature as cations with +1oxidation state . Therefore , they readily form salts with non-metals
• Ans 2: The alkaline earth metals are smaller and have more nuclear charge . They have two electrons in their valence shell i-e ns². They are also reactive but less than alkali metals

Why nitrogen is necessary for safety of life on earth ?

• Ans 1:
  Nitrigen is 78% in atmosphere and is necessary for safety of life on earth . It controls the fire and combustion process ,
  otherwise all the things around us could burn with a single flame
  
  

What is kept constant in Charles law ?

• Ans 1: Pressure is kept constant in Charles law

How many times is 1 mole of oxygen atom heavier than 1 mole of hydrogen atom?

• Ans 1: One mole of oxygen atom is 16 times heavier than the one mole of hydrogen.

Why shielding effect of electron makes action formation easy ?

• Ans 1: As we move down in a group more and more shells come come between valence shell and the nucleus of atom , additional shell reduce the electrostatic force of attraction felt by the electron present in the outermost shell , and the shielding effect increases resultantly , and the electrons can be taken away , easily and cations form

Why nitrogen forms compounds with alkaline earth metals directly ?

• Ans 1: A alkaline earth metals from stable nitrides when heated with nitrogen
• Ans 2: 3Mg + N₂➜Mg₃N₂

Why solution is considered mixture ?

• Ans 1: The chemical reaction did not take place between the components of solution and the components kept constant their properties . That's way solution is considered mixture .

Who discovered proton , electron , neutron ?

• Ans 1: In 1886, Goldstein discovered positively charged particles called protons . In 1897 , J.J Thomson found in an atom , the negatively charged particles known as electron . In 1932 James Chadwick discovered neutron

What is the nature of electrode used in electroplating chromium ?

• Ans 1: During electroplating chromium the object to be electroplated act as cathode with anode is made up of antiamonial lead

Complete and balance the given chemical equation Na + H₂➜ ?

• Ans 1: 2Na + H2➜ 2NaH
  (Sodium ) (Hydrogen ) (sodium hydroxide )

Which form of Sulphur exists at room temperature?

• Ans 1: Rhombic (S₈) Sulphur exists at room temperature

Why does reactivity of metals increase down the group?

• Ans 1: The reactivity of metals increase down the group due to increase in atomic size and shielding effect down the group . The ability of the metals to loose electrons increase down the group and ionization energy also decrease hence their reactivity increase down the group

Define reduction on the basis of electron and give example .

• Ans 1: Reduction reaction : The gain of electrons by atom or ion is called reduction reaction .
• Ans 2: Example : Cl_(g) + le^-➜ Cl^- _(g)
• Ans 3: In above reaction , a chlorine atom is changed into a chlorine ion through reduction . Hence it is approved that conversion of an atom into ion is a reduction reaction

Write any two properties of solution and suspension

• Ans 1: Solution :
  1: A solution is a homogeneous mixture of two or more substances
• Ans 2: 2: The boundaries of compounds cannot be distinguished i-e a solution exist as one phase
  Example : Sugar dissolved in water is an example of liquid solution
• Ans 3: Suspension :
  1: Suspension is heterogeneous mixture in which the solute particles remain undissolved in the medium
• Ans 4: 2:Particles of solute are too big enough to be seen with naked eye
  Example : Chalk in water , paint , milk of magnesia

Write the percentage of volume by weight of oxygen in atmosphere and oceans

• Ans 1: In atmosphere oxygen is 21% while in oceans it is 86%

Why HF is a weak acid ?

• Ans 1: HF is a weak acid because in HF -compound . There is strong intermolecular bonding . So, it does not readily ionize in water and release H+ in water the strong acid is that which is readily ionized in water but HF does not easily ionized in water

Convert the following. Ans: a) 70 cm lig to atm. b) 3.50atm to torr. c) 1.5 atm to Pa.

• Ans 1:
  70 cm Hg to atm
  We know that
  76 cm 11g= 1 atm
  1 em = 1/76 atm
  70 cm Hg = 1/76. 70atm
  70 cm lig =0.92 atm
  
  
• Ans 2:
  b :3.50atm to torr.
  We know that 1 atm = 760 torr
  3.5atm = 3.5 x 760torr 3.5 atm = 2660torr
  
  
• Ans 3:
  c: 01.5 atm to Pa
  We know that 1 atm = 101325 Pa
  1.5alm = 101325. 1.5 Pa
  1.5 atm 151987.5 Pa
  1.1 atm = 151987.5 Pa
  
  

Molecular formula of a sulphur molecule

• Ans 1: The Molecular formula of a sulphur molecule S₈

What is meant by element ? Explain with example .

• Ans 1: Element is a substance which is made up of some types of atom , having same atomic number and it cannot be dissolved into simple substances by ordinary chemical means
• Ans 2: Example Sodium (Na) , Oxygen (O)

Define Boyle's law .

• Ans 1: According to Boyle's law the volume of a given mass of a gas is inversely proportional to its pressure at constant temperature .
• Ans 2: Mathematical expressions of Boyle's law :
  V∝ 1/P
  V∝ k/p
  VP = k

In what conditions H2 reacts with l2 ? Give equation of the reaction .

• Ans 1:
  H2 reacts with l2 on heating and in the presence of catalyst to produce hydrogen iodide
  H2 + l2 ➜ 2Hl
  
  

What is the trend of variation in densities of alkali metals?

• Ans 1: Densities of alkali metals increases down the group in the periodic table

What is vapour pressure ?

• Ans 1: The pressure exerted by the vapour of a liquid at equilibrium with the liquid at a particular temperature is called vapour pressure of liquid
• Ans 2: At high temperature vapour pressure is higher than at low temperature and K.E molecule increase

Define Industrial Chemistry and Analytical Chemistry.

• Ans 1: Industrial Chemistry: "This branch of chemistry is related to the the industrial processes" It is associated with studies of properties uses and application of techniques for the preparation of industrial sales on large scale.
• Ans 2: Analytical Chemistry:It deals with the detection and estimation of elements and compounds. In this the composition of elements is primarily analysed."

Difference between molecular mass and formula mass.

• Ans 1: Molecular Mass:
  The sum of the atomic mass of all the elements present in a molecule is called as Molecular Mass.
  
  
• Ans 2: Formula Mass:
  The sum of atomic masses of all the elements present in a formula unit of an ionic compound is called formula mass.

Which factor controls the non-metallic character of the element?

• Ans 1: The non - metallic character of elements is depending upon the electron affinity and electron affinity and electronegativity

Give the composition of Earth Crust with respect to three major elements.

• Ans 1: Earth Crust is formed by three major elements having following percentages. Oxygen 47% Silicon 28% Aluminum 7.8%

What is difference between Duplet rule and octet rule ?

• Ans 1: Duplet rule : Attaining two electrons in the valence shell is called duplet rule
• Ans 2: Octet rule : Attaining eight electrons in the valence shell is called octet rule

For an element Z = 92 A = 238 Calculate number of neutron in it

• Ans 1: Atomic mass = No of protons + No of neutrons =A=238
  No of protons Z = 92
  
  No of neutrons =N=A-z
  =238-92= 146

Name a metal which can be cut with knife?

• Ans 1: Sodium is that metal which can be cut with knife, because it is soft.

What will happen if the pressure temperature is kept constant?

• Ans 1: The volume of gas will decrease three times when its pressure raised up to three times as temperature.

Can pure gold be used for making ornaments?If not why?

• Ans 1:
  No. pure gold cannot be used for making ornaments.
  because gold is too sift to be used as such It is always alloyed with copper. silver and some other metals
  
  

How many molecules of water are present in half mole of water ?

• Ans 1: Water molecules in half moles = 1/2x6.02x10²³
  = 3.01x10²³ molecules

If 16g of oxygen contains 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams

• Ans 1: 16g of oxygen =1 mol of oxygen
  Mass of one atom of oxygen = 16 grams

What is meant by true solution ?

• Ans 1: True solution are the homogeneous mixture of two or more than two components . Each components is mixed in such a way that their individual identity is not visible
• Ans 2: Example : Its simple example is a drop of solvent ink in water

Why the ionization energy of Na is more than K?

• Ans 1: Ionization energy of sodium is more than K because down the group electropositive character increases and ionization energy decreases. As it become easier to remove electron' down the group

Differentiate bonding electrons and non-bonding electrons•

• Ans 1: The valence electrons which are involved in chemical boding, are termed as bonding electrons. e.g.
  The valence electron of sodium is bonding electrons
  ₁₁Na K L M
  2 8 1
• Ans 2: Non Bonding: The electrons of an atom which do not participate in bonding called non - bonding electrons
• Ans 3: Example :
  The first and second shell electron are non- bonding electrons
  ₁₁Na K L M

  2 8 1

Calculate the formula mass of the sodium sulphate .

• Ans 1: Formula mass of the sodium sulphate :
  Na2so4 =2(23) +(32)+4(16)
  =46+32+64
  =142amu

Why does Aluminium not rust ? Explain

• Ans 1: Aluminium corrodes but it does not rust because a very hard material aluminium oxide , protects the aluminium from rust and further corrosion . Rust refers only to iron and steel corrosion . Whenever , iron corrodes its colour changes that exposes iron to further rusting

Which allotropic form of carbon is stable at room temperature (25°C)?

• Ans 1: Graphite is more stable at room temperature

How many atoms are present in one gram atomic mass of a substance?

• Ans 1: One gram atomic mass of a substance is equal to Avogadro's number in which 6.023 x 1023 atoms are present

Define groups ?

• Ans 1: The vertical columns in periodic table are called groups . Numbered from 1 to 18

Why are the colloids quite stable ?

• Ans 1: In colloid particles are large but not large enough and they are stabilized hence they do not settle down for a ling time that is why colloids are quite stable

What is diffusion ? Explain with example .

• Ans 1: Diffusion : The process in which molecules more from the area of higher concentration move to the area of lower concentration until the state of equilibrium is achieved is called diffusion
• Ans 2: Example : If we open perfume bottle in the corner of the room , the fragrance of perfume spread in whole room by diffusion

Differentiate between homoatomic and heteroatomic molecules with examples .

• Ans 1: Homoatomic molecules : A molecule containing same type of atoms is called homoatomic molecule
• Ans 2: Example : H₂ O₃ S₈
• Ans 3: Heteroatomic molecules : A molecule containing different kinds of atoms is called heteroatomic molecule
• Ans 4: Example : CO₂ ,H₂O ,NH₃

Define Triatomic molecule and polyatomic molecule

• Ans 1: Polyatomic molecule : The molecules which consists of many atoms calledpolyatomic molecule
• Ans 2: For example : C6H12O14 glucose N2H4 hydrazine
• Ans 3: Triatomic molecule: The molecules which consists of three atoms called
  triatomic molecule
• Ans 4: For example : H2O , CO2

Which term is used to represent the mass of 1 mole of molecules of a substance?

• Ans 1: Gram molecular mass

What is free radical ? Give example.

• Ans 1: Free radical : Free radical are atoms or groups of atoms possessing odd number (unpaired ) electrons.
• Ans 2: Explanation and example : It is represented by putting a dot over the symbol of an element e.g H., Cl2. , H3C. Free radicals are generated by the homolytic (equal) breakage of the bond between 3 two atoms when they absorb heat or light energy . A free radical is extremely reactive species as it has the tendencyto complete its octet
• Ans 3: Reactions : Molecules Free radicals
  Cl2 ➜ 2Cl.
  CH4➜ H3C. + H.

Write two properties of gases

• Ans 1: 1: Molecules of gases are always in state of continuous motion . They have very high K.E .
• Ans 2: 2: Gases have very low density therefore , they have large volume

Define empirical formula and give examples.

• Ans 1: It is the simplest whole number , ratio of atoms present in a compound." Empirical formula of benzene Empirical formula of Hydrogen peroxide

Where sodium metal is obtained from fused sodium chloride .

• Ans 1: Sodium metal accumulates at iron cathode in down's cell

Where does most of the mass of an atom exists ?

• Ans 1: Most of the mass of an atom exists in its nucleus . The sum of masses of protons and neutrons is equal to atomic mas of an atom

Name the metal which is the poorest conductor of heat ?

• Ans 1: Lead is the poorest conductor of heat

Which factors affect the non-metallic character ?

• Ans 1:
  Non-metallic character depends upon Electron affinity and electronegativity
  
  

State three reasons why do you think air is a mixture and water a compound

• Ans 1: Air (mixture)
  1: Mixture is formed by the simple mixing up of the substances
  2: Air does not have a sharp and fixed melting point
  3: Air has heterogenous mixture composition
• Ans 2: Water (Compound) :
  1: It is formed by the chemical combination of atoms of elements
  2: Water has a sharp and fixed melting point
  3: Water has homogenous composition

Write down names of two very reactive metals .

• Ans 1: 1: Li (Lithium)
• Ans 2: 2: Na (Sodium)

Differentiate between homoatomic and heteroatomic molecules with examples .

• Ans 1: Homoatomic molecules : A molecule containing same type of atoms is called homoatomic molecule
• Ans 2: Example : H₂ O₃ S₈
• Ans 3: Heteroatomic molecules : A molecule containing different kinds of atoms is called heteroatomic molecule
• Ans 4: Example : CO₂ ,H₂O ,NH₃

What is quantum ?

• Ans 1: Quantum means fixed energy . It is the smallest amount of energy that can be emitted or absorbed as electromagnetic radiation

Why are the liquids mobile.

• Ans 1: Liquid molecules are in continuous state of motion. They possess high kinetic energy and have weak intermolecular forces than solids That's why liquids are mobile

Why is white tin available at room temperature?

• Ans 1: White tin available at room temperature because it is stable at room temperature above 13.2°C

Why do the isotopes of an element have different atomic number masses?

• Ans 1: As isotopes of an element have same atomic mass . Mass number depends upon number of protons and neutrons . Isotopes of an element have the same number of proton but only differ in their neutrons number

Define metallic character .

• Ans 1: The property of a metal to loose its valence electrons to form a positive ion is called metallic character
• Ans 2: Na➜ Na⁺ +1e^-

Why is melting point of a solid considered its 'identification' characteristics ?

• Ans 1: The melting point of a solid considered its identification because pure solids have a sharp and specific melting point , no other solid has same melting point

Why are the rates of diffusion in liquids slower than that of gases?

• Ans 1: In liquid molecules intermolecular forces are stronger than gases and there molecules are, closer to each other. Asa result rate of diffusion in liquids are slower than gases.

How many electrons are present in sub-shell ?

• Ans 1: s can have 2 electrons
  p can have 6 electrons
  d can have 10 electrons
  f can have 14 electrons

Differentiate between Lone pair and bond pair of electrons .

• Ans 1: Long pair : The pair of electrons which remain unshared during covalent bond formation is called long pair
• Ans 2: Bond pair : Shared pair of electrons in the covalent bond called bond pair

What is tyndall effect ? On which factor it depends ?

• Ans 1: Tydnall effect: The particles of colloids are big enough to scatter the beam of light . It is called tydnall effect
• Ans 2: Factors depends upon tydnall effect :
  It depends upon size of solute particles

Why atomic number is more fundamental property to arrange elements than atomic mass?

• Ans 1: Due to two reasons :
  1: It increase regularly from element to element
• Ans 2: 2: It is fixed for every element

How does homogeneousmixture differ from heterogeneous mixture?

• Ans 1: The mixture that has uniform composition throughout is called homogeneous mixture which composition is not uniform throughout e.g. soil, rock and wood etc.

Which one has more molecules : 9 g of water or 9 g of sugar C₁₂ H₂₂ O₁₁ ?

• Ans 1: 9g of water has more molecules than 9 g of sugar because moles of water are more than sugar
  For water
• Ans 2: Number of molecules = Mass/ molar mass x N_A
  _{= 9/18 X 6.02 X 10}²³
  = 3.01 X 10²³
• Ans 3: For sugar (C₆ H₁₂O₆ )
  
  
  Number of molecules : mass / molar mass x N _A
  = 9/18 X 6.02 X 10²³
  = 3.01 X 10²³
• Ans 4: Result : 9 g of H2O has more molecules than 9g of C₆H₁₂O₆

What do you mean by induced dipole?

• Ans 1: The charges in one molecule creates charges in other molecules these charges are called induced dipole.
  

Which has more atoms :10g of Al or 10 g of Fe ?

• Ans 1: 10 g of A 1 has more atoms than 10 g of Fe
  For A 1
  
  
• Ans 2: Number of atoms = Mass/molar mass x N _A
  _{= 10/23 X 6.02 X 10}²³
  = 2.617X10²³
• Ans 3: For Fe :
  Number of atoms = Mass/molar mass x N _A
  = 10/56 X 6.02X10²³
  = 1.075 X 10²³
  
  

What is the nature of charge on cathode rays ?

• Ans 1: Their deflection in electric and magnetic field proves that they have negative charge

Write two properties of liquid state of matter

• Ans 1: 1: Liquid have fixed volume but no fixed shape . It attains the shape of container in which it is kept
• Ans 2: 2: The particles of liquid are much farther a part than those of solids

Write down the position of hydrogen in the periodic table

• Ans 1: First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period

Why do the colloids show tydnall effect ?

• Ans 1:
  Colloids shows tyndall effect because the particles of
  ” colloids scatter the path of light rays due to large size.

Define periods ?

• Ans 1: Seven horizontal rows present in periodic table are called periods . Numbered from 1 to 7

What do you mean by horticulture and how it is related agriculture ?

• Ans 1: It deals with the art of gardening . A horticulture works fir the betterment of existing varieties and for the production of new varieties of ornamental plants and fruits plants

Why shielding effect of electron makes cation formation easy ?

• Ans 1: Shielding effect reduce the effective nuclear charge due to the nucleus thus the net force on the valence electrons decrease due to higher shielding effect . That is why the removal of valence electron become easy for cation formation

Why the liquid molecules are mobile ?

• Ans 1: Liquid molecule have less intermolecular forces as compared to solids , which are not able to stable molecules of liquid at a fixed points . That is why liquid molecules are mobile

Write example of use of radioactive isotopes in the field of medicine and radiotherapy

• Ans 1: In the field of medicine isotopes of iodine I -131 are used for diagnosis of goiter in thyroid gland . While P-32 and Sr 90 are used in the field of radioactivity

Define evaporation and give example ?

• Ans 1: Evaporation: The conversion of liquid into vapours called evaporation .
• Ans 2: Example : When a mole of water in liquid state is converted from it required 40.7kJ/mol of energy
• Ans 3: H₂O(g)➜H2O(g)△H = 40.7kJ/mol

Differentiate between boiling and melting point .

• Ans 1: Melting point : The temperature at which the solid starts melting and exist in dynamic equilibrium with liquid state is called melting point
• Ans 2: Boiling point : Boiling point is defined as the temperature at which the vapour pressure of a liquid become equal to the atmospheric pressure or any external pressure

How is periodicity of properties dependent upon the number of protons in an atom ?

• Ans 1: In periodic table from left to right number of protons increases . Due to change in nuclear charge the properties of an atom were found repeating after regular intervals . Hence periodicity of properties dependent upon the number of proton in an atom

How iron is prevented from rust by tin coating ?

• Ans 1: 1:It involves the dipping of the clean sheet of iron in a bath of molten tin and then passing it through hot rollers
• Ans 2: 2: Such sheets are used in the beverage and food cans
• Ans 3: 3: The tin protects the iron only long as its protective layer remains intact . Once it is broken and the iron is exposed to the air and water , a galvanic cell is established and iron rusts rapidly

Why do suspensions not form the homogeneous mixture ?

• Ans 1: The force of attraction does not develop between particles of solvent and solute in the suspensions , due to this , suspension does not from homogeneous mixture

Where sodium metal is obtained from fused sodium chloride .

• Ans 1: Sodium metal accumulates at iron cathode in down's cell

Which term is used to represent the mass of 1 mole of molecules of a substance?

• Ans 1: Gram molecular mass

Why ionic compounds easily dissolve in water?

• Ans 1: They dissolve easily in water because water is a polar solvent and has high dielectric constant that weakens the attraction between ions.

Write any two properties of solution and suspension

• Ans 1: Solution :
  1: A solution is a homogeneous mixture of two or more substances
• Ans 2: 2: The boundaries of compounds cannot be distinguished i-e a solution exist as one phase
  Example : Sugar dissolved in water is an example of liquid solution
• Ans 3: Suspension :
  1: Suspension is heterogeneous mixture in which the solute particles remain undissolved in the medium
• Ans 4: 2:Particles of solute are too big enough to be seen with naked eye
  Example : Chalk in water , paint , milk of magnesia

In which branch of chemistry behaviour of gases and liquid is studied ?

• Ans 1: The bahaviour of gases and liquid is studied in the branch of chemistry called physical chemistry

Describe at least two necessary conditions for the formation of covalent bond .

• Ans 1: 1: A covalent bond is formed between two non-metals
• Ans 2: 2: Electronegativity difference between combining atoms of non-metals must be very low
• Ans 3: 3: The two combining atoms should have high ionization energy

Give uses of platinum

• Ans 1:
  Uses of platinum :
  1: Platinum is used in hard disk coating and in maufacturing fibre optic cables
  
  
• Ans 2:
  2: Platinum is used in making jewellery .
  
  
• Ans 3: 3: Platinum is also used in making plastic of fiberglass and glass of LCD

How does homogenous mixture differ from heterogenous mixture ?

• Ans 1: Homogenous mixture : Mixtures that have uniform composition through are called homogenous mixture
• Ans 2: Heterogenous mixture : Those mixtures in which composition are not uniform throughout are called Heterogenous mixture

What is teh relationship between mass and mole of a substance?

• Ans 1: The relationship between mass and mole of substance is given as following mass of substance = No of moles x Molar mass of substance

Human body made up of how many elements ? Write their names .

• Ans 1: Six elements constitute about 99% of our body mass , oxygen 65% , Carbon 18% , Hydrogen 10% , Nitrogen 3%, Calcium 1.5% and phosphorous 1.5% , Potassium , Sulphur , Magnesium and sodium constitute 0.8 % of our body mass . Wherease copper , zinc , chlorine , fluorine , iron , cobalt and magnesium constitute only 0.2% of our body mass

Write chemical formula of Aluminium sulphate and Calcium phosphate .

• Ans 1: Aluminium sulphate: Al2(SO4)
• Ans 2: Calcium phosphate: Ca3 (PO4)2

What is the empirical formula of acetic acid (CH₃COOH)? Also calculate the molecular mass of acetic acid .

• Ans 1: Empirical formula of acetic acid is CH₂O
• Ans 2: molecular mass of acetic acid (CH₃COOH):
  Atomic mass of C =12 amu
  Atomic mass of H = 1 amu
  Atomic mass of O = 16 amu
  Molecular formula (CH₃COOH)
  Molecular mass = 2 (At.Mass of C ) + 4(At,Mass of H ) +2 (At.Mass of O )
  =2(12) + 4(1) + 2(16)
  = 24 + 4 + 32
  = 60 amu

Describe the chemical reaction of alkaline earth metals with hydrogen .

• Ans 1: Alkaline metals :
  Reaction with oxygen :
  1: Alkaline metals immediately tarnish in air giving their oxides which form strong alkalies in water
  4Na +O➜ 2Na2 O
  Na₂ O➜ 2NaOH
  2: Reaction with hydrogen :
  The form ionic hydrides with H₂at high temperature
  2Na +H₂➜2NaH
  Reaction with Halogens :
  3: They react violently with halogens at room temperature to give halides
  2Na +Cl₂➜ 2NaCL
• Ans 2: Alkaline earth metals
  1: Alkaline earth metals are less reactive toards oxygen and oxides are formed on heating
  2Mg +O➜ 2MgO
• Ans 3: 2: They give hydrides under strong conditions of temperature and pressure
  Ca +H➜ CaH₂
• Ans 4: 3: They react slowly with halogens to give their halides
  Ca+Cl₂➜ CaCl₂

Write two properties of crystalline solids .

• Ans 1: 1: In crystalline solids particles are arranged in definite in definite pattern .
• Ans 2: 2: They have definite geometrical shape
• Ans 3: 3: They have sharp melting point

How atoms accommodate 8 electrons in their valence shells?

• Ans 1: toms can accommodate 8 electrons in their valence shell in three.
  1: By giving valence shell electrons
  2:By gaining valence shell electrons
  3:By sharing valence shell electrons with other atoms

Why do ionic compounds conduct electricity in solution or molten form?

• Ans 1: Ionic compounds are good conductor in solution and molten form due to the presence of free ions in them

Is the Boyle's law valid at very high temperature?

• Ans 1: No. Boyle's law is not valid at very high temperature

Define metallic character .

• Ans 1: The property of a metal to loose its valence electrons to form a positive ion is called metallic character
• Ans 2: Na➜ Na⁺ +1e^-

Differentiate between homogenous and heterogenous mixture .

• Ans 1: Homogenous Mixture : Mixtures that have have uniform composition throughout are calledhomogenous mixture
• Ans 2: For example : Milk , air , brass, ice-cream
• Ans 3: Heterogenous mixture: Mixture which does not have uniform composition throughout is calledheterogenous mixture
• Ans 4: Examples : Soil, Wood

Why is galvanizing done?

• Ans 1: The process of coating a thin layer of zinc or iron is called galvanizing. Galvanizing is dot, because zinc protects the iron against corrosion even after the coating surface is broken.

Define the term allotropy ?

• Ans 1: Allotropy: The existence of an element in more than one forms in same physical state is called allotropy.

Why are the rates of diffusion in liquids slower than that of gases?

• Ans 1: In liquid molecules intermolecular forces are stronger than gases and there molecules are, closer to each other. Asa result rate of diffusion in liquids are slower than gases.

What is pacemaker ?

• Ans 1: A pacemaker is a small device in which body fluids act as an electrolyte . This device uses electrical pulses to prompt the heart to beat at a normal rate

Write two difference between atom and anion

• Ans 1: Ion :
  1: It is the simplest unit of ionic compound
  2: It has net charge either negative or positive on it
• Ans 2:
  Atom
  1: It is the smallest particle of an element
  2: It has no net charge , It is electrically neutral

Who discovered proton , electron , neutron ?

• Ans 1: In 1886, Goldstein discovered positively charged particles called protons . In 1897 , J.J Thomson found in an atom , the negatively charged particles known as electron . In 1932 James Chadwick discovered neutron

What is the colour of flame when sodium and calcium burn in air ?

• Ans 1: 1: Sodium burns in air and produce golden yellow flame
• Ans 2: 2: Calcium burns in air and produce Brick Red Flame

Why the boiling point of water higher than alcohol?

• Ans 1: Water has ability to form two hydrogen bonds while Ethyle alcohol has ability to form one hydrogen bond . That's why the boiling point of water is higher than alcohol

Write difference between saturated solution and unsaturated solution .

• Ans 1: Saturated solution : The solution containing maximum amount of solute at a given temperature is called saturated solution
• Ans 2: Unsaturated solution : A solution which contain lesser amount of solute which is required to saturate a solution at particular temperature .

What is difference between colloidal and suspension ?

• Ans 1: Colloid : The particles of colloid are large consisting of many atoms , ions or molecules . Particles are large but can't be seen with naked eye
• Ans 2: Suspension : The particles of suspension are of largest size . They are larger than 10^-5 cm in diameter . Particles are big enough to be seen with naked eye

Why densities of gases are less than liquids ?

• Ans 1: Gases have low density than liquids and solids . It is due to light mass and more volume occupied by the gas molecules . Gas density is expressed in grams per dm³. Whereas liquid and solid densities are expressed in grams per cm³ i-e liquids and solids are 1000 time denser than gases
• Ans 2: Example : At normal atmospheric pressure , the density of oxygen gas is 1.4g dm^-3 at 20° C and 1.5 gdm^-3 at0°C

What is general principle of solubility ?

• Ans 1: The general principle of solubility is ' like dissolve like ' . The polar substance dissolve in polar substance and non-polar substances and non-polar substances dissolve in non-polar substance

Write the redox reaction taking place during the electroplating of chromium .

• Ans 1: Chromium sulphate Cr(SO₄)₃ used as an electrolyte in the electroplating of chromium that provides CCr⁺³ ions which reduce and deposit at cathode
• Ans 2: The following reactions take place at both electrodes
• Ans 3: Reaction at anode : 4OH^- _(aq)➜ 2H₂O ₍₁₎ + O₍₁₎ +O2_(g)+4e^-
• Ans 4: Reaction at cathode : Cr₃+ _(aq) + 3e^-➜Cr _(s)

Difference between oxidation state and valency

• Ans 1: Oxidation : Oxidation state is apparent charged assign to an atom of an element in a molecule or an ion .
  While assigning O.S the sign precedes the number
  e.g +2
• Ans 2: It is the combining capacity of one element with other element
  While writing valency sign following by the number
  2+

Identify strong or weak electrolyte among the following

CuSO₄ , H2CO₃ ,(OH)₂ , AGNO₃ , Ca (OH)₂

• Ans 1: Strong electrolyte :HCL,HNO₃ and CuSO₄. AgNO₃ are strong electrolyte
• Ans 2: Weak electrolyte: H2CO3. Ca (OH)₂ is weak electrolyte

hat is the importance of oxygen and carbon dioxide for plants and animals ?

• Ans 1:
  Life owes to non-metals as without O2 and CO2 those are essential gases for respiration of animals and plants respectively , life would not have been possible . In fact these
  gases are essential for the existance of life

Difference between homogeneous and heterogeneous mixture.

• Ans 1: Homogeneous mixture: Mixtures that have uniform composition throughout are called homogeneous mixtures.
  example: Milm, Brass, Ice-cream.
• Ans 2: heterogeneous mixture: Mixture which does not have uniform composition throughout is called heterogeneous mixtures.
  example: Soil,Wood

Write the redox reaction taking place during the electroplating of chromium.

• Ans 1: Reaction at the electrodes are as Follows:
  At anode 40H-➜2H₂O+O₂+4e^-
  At cathode C⁺³3e^-➜Cr

What is difference between group and period ?

• Ans 1: Group : The vertical columns present in periodic table are called groups .There are 18 groups present in the periodic table
• Ans 2: Period: The horizontal rows present in periodic table are called period .There are 7 periods present in the periodic table

Which factor controls the non-metallic character of the element?

• Ans 1: The non - metallic character of elements is depending upon the electron affinity and electron affinity and electronegativity

Why sodium metal is more reactive than magnesium ?

• Ans 1: Magnesium is harder then sodium because density of sodium is 0.98cm ^-3 and density of magnesium is 1.74gcm³ . Sodium is too soft to be cut with knife

How many elements are in 3rd period, write their names and symbols?

• Ans 1: There are eight elements in 3' period, sodium(Na), magnesium(Mg) .aluminium (AI).silicon(Si),phosphorus(P),sulphur(S),chlorine(Cl),argon(Ar)

Write down the electronic configuration of following

1: Na 2: Al

• Ans 1: 1: Atomic number of Na 11
  ₁₁Na = 1s². 2s² . 2p⁶ . 3s¹
• Ans 2: 2: Atomic number of A1 13
  ₁₃Al = 1s². 2s² . 2p⁶ . 3s³

Write down the two postulates of Bohr's atomic model .

• Ans 1: 1: The hydrogen atom consists of a tiny nucleus and electrons are revolving in one of circular orbits of radius ' r ' around the nucleus
• Ans 2: 2: Each orbit has a fixed energy that is quantized

What is the reason of deficiency of electrons in BF_3?

• Ans 1: In the formation ofBF₃molecules , three valence electrons of boron (B) make three pairs of mutual coordination with three valance electrons from three fluorine atoms .. Despite of covalent bond made due to this mutual coordination , there is still deficiency of electron in boron . That's why octate is still incomplete (BF₃)
• Ans 2: Formation of coordinate covalent bond in BF₃ and NH₃, If an ammonia molecule (NH₃) which has lone pair come close to the boron tri fluoride molecule (BF₃) then ammonia give a lone pair to boron tri fluoride (BF₃) to fulfil the deficiency of electrons . In this way NH₃ become electron pair donor and BF₃ become electron pair acceptor

What is matter ? How many states it has ?

• Ans 1: Matter is any thing that has mass and occupies space .
• Ans 2: State of matter :
  1: Solid
• Ans 3: 2: Liquid
• Ans 4: 3: Gas

What is the trend of electronegativity in the period ?

• Ans 1: The trend ofelectronegativity is same as of ionization energy and electron affinity . It increases in a period from left to right because higher Z_eff shortens distance from the nucleus of the shared pair of electrons . This enhances the shared pair of electron

Magnesium has electronic configuration 2,8,2

a: How many electrons are in outermost shell ?

b: In which sub-shell of outermost shell electrons are present ?

c: Why magnesium tends to lose electron ?

• Ans 1: a: There are two electrons in outermost shell
  b : In sub-shell of outermost shell electron are present
  1s² , 2s² , 2p⁶ .3s²
• Ans 2: c: Because Mg is an electropositive element having tendency to lose electron .So it loses its outermost 2 electrons and became MG ⁺²

Give the electronic configuration of carbon atom.

• Ans 1: Atomic no. of carbon = Z= 6
  No of electrons in carbon atom =Z=6
  Electronic configuration of carbon atom=ls².2s²,2p²

Why are the liquids mobile.

• Ans 1: Liquid molecules are in continuous state of motion. They possess high kinetic energy and have weak intermolecular forces than solids That's why liquids are mobile

Define ionization energy .

• Ans 1: Ionization energy is the minimum amount of energy required to remove the most loosely bound electron from the valence shell of an isolated gaseous atom

Why noble gases are non-reactive?

• Ans 1: The noble gases do have 2 or 8 electrons in their valence shells. It means all the noble gases have their valence shells completely filled. Their atoms do not have vacant space in their valence, shell to accommodate extra electrons. Therefore noble gases do not gain. lose or share electrons. that's why they are non - reactive

What are shells ?

• Ans 1: Shells are specific energy levels around nucleus in which electron resolve
  e.g K,L,M,N

What is the principle of electroplating ?

• Ans 1: Principle of electroplating is to establish an electrolytic cell in which anode is made of the metal to be deposited and cathode of the object on which metal is to deposit . The electrolyte is an aqueous solution of salt of the respective metal

Which is the simplest form of matter?

• Ans 1: Gas is the simplest form of matter.

What is the atomic number , how it is represented ?

• Ans 1: The atomic number of an element is equal to the number of protons present in the nucleus of its atoms
• Ans 2: Representation : It is represented by 'Z'

Ionic bond is stronger than covalent bond . Explain .

• Ans 1: Ionic bond formed between two opposite charges and electrostatic forces . That's why ionic compound is stronger than covalent bond

Write the redox reaction taking place during the electroplating of chromium .

• Ans 1: Chromium sulphate Cr(SO₄)₃ used as an electrolyte in the electroplating of chromium that provides CCr⁺³ ions which reduce and deposit at cathode
• Ans 2: The following reactions take place at both electrodes
• Ans 3: Reaction at anode : 4OH^- _(aq)➜ 2H₂O ₍₁₎ + O₍₁₎ +O2_(g)+4e^-
• Ans 4: Reaction at cathode : Cr₃+ _(aq) + 3e^-➜Cr _(s)

Write down the name of four least reactive metals .

• Ans 1: The names of least reactive metals are following
• Ans 2: 1: Gold
• Ans 3: 2: Silver
• Ans 4: 3:Platinim
• Ans 5: Copper

Identify strong or weak electrolyte among the following

CuSO₄ , H2CO₃ ,(OH)₂ , AGNO₃ , Ca (OH)₂

• Ans 1: Strong electrolyte :HCL,HNO₃ and CuSO₄. AgNO₃ are strong electrolyte
• Ans 2: Weak electrolyte: H2CO3. Ca (OH)₂ is weak electrolyte

What do you mean by malleability?

• Ans 1: Malleability is the property by virtue of which metals can be drawn into sheets.

Differentiate between nuclear chemistry and environmental chemistry .

• Ans 1: Environmental chemistry:
  1 :The branch of chemistry in which we study about components of the environment and effect of human activity on the environment
  2 :it is also concerned with other sciences like biology, geology

  3: Save environment from pollution
  

  
  
• Ans 2: Nuclear chemistry:
  1: The branch of chemistrythat deals with the radioactivity nuclear processes and properties
  2: The main concern of this branch is with the atomic energy and its uses in daily life
  3: It is used in radiotherapy , in the preservation of food and in industry
  

  
  

  
  

Which term is used to represent the mass of 1 mole of molecules of a substance ?

• Ans 1: Gram molecular mass

What are non - electrolytes .Give one example

• Ans 1: The substances , which do not ionize in their aqueous solutions and do not allow the current to pass through their solutions are called non-electrolytes
• Ans 2: For example : sugar solution and benzene are non - electrolytes

What is meant by variable valency?

• Ans 1: Some elements show more than one combining power that is called variable valency for example, in Ferrous sulphate the valency of Iron is 2 whereas in ferric sulphate the valency of iron is 3

Electronic configuration of Cl^- ion

• Ans 1: Cl^-1s² ,2s²,2p⁶ ,3s² ,3p⁶

Why 2nd ionization energy of an elements is higher than first one?

• Ans 1: fins: energy required to remove an electron from isolated mono positive gaseous ion (M') is called second ionization energy. So more energy is required to remove second electron from a mono positive gaseous ion because there is more electrostatic force present between the nuclei and electron. M⁺➜M⁺²1e^-

Write down atomic number of nitrogen and oxygen .

• Ans 1: The atomic no of N₂ is = 7
• Ans 2: Electronic configuration of ₇N = 1s² , 2s² , 2p³
  ^{The atomic no of 0}₂is =8
• Ans 3: Electronic configuration of ₈O = 1s² , 2s² , 2p⁴

A long as electron remains in an orbit , it does not emit or absorb energy , when does it emit or absorb energy ?

• Ans 1: When an electron jumps from lower orbit to higher orbit . It absorbs energy and when it jumps from higher orbit to lower orbit . It radiates energy . This change in energy ,

  △E given by following Plank's equation

• Ans 2:

  △E =E2-E1=hv where h is a plank's constant equal to 6.63x10-34Js and π is frequency of light

Differentiate between ions and free radicals ?

• Ans 1: Ions :
  1: These are atoms which bear some charge
  2: They exists in solution or in crystal lattice
  3: Their formation is not affected by the presence of light
• Ans 2: Free radicals:
  1: These are the atoms that have odd number of electrons
  2: They can exist in solutions as well as in air
  3: They may form in the presence of light

iodine exists in solid state, can it be beaten with hammer to form sheets?

• Ans 1: No, only solid metals have the characteristic to be beaten with hammer to for sheet

Define atomic radius ?

• Ans 1: The half of the distance between the nuclei of the two bonded atoms referred as atomic radius

Write two examples of gas into gas solution .

• Ans 1: 1:Air
  
• Ans 2: 2: Mixture of H₂ and He in wheather ballons
• Ans 3: 3: Mixture of N2 and O2 in clinders for respiration

Which force drives the non-spontaneous reaction to take place ?

• Ans 1: Non-spontaneous reactions are those which take place in the presence of an external agent . These reactions takes place in galvanic and electrolytic cells
• Ans 2:
  

State John Dalton's atomic theory .

• Ans 1: Main points of John Dalton's atomic theory are given as follows
• Ans 2: 1: An atom is an indivisible , hard , dense spherical particle
• Ans 3: 2: Atoms of the element are alike
• Ans 4: 3: Atoms combine in different ways to form compounds

Which are physical properties of matter ?

• Ans 1: 1: Matter exists in three physical state i-e gas, liquid , and solid
• Ans 2: 2: The simplest form of matter is the gaseous state
• Ans 3: 3: Liquids are less common and most of the matter exists as solid

Define oxidation and give example .

• Ans 1: Oxidation reaction : The loss of electron by an atom or ion is called oxidation .
• Ans 2: 1: Example : Za➜ Zn⁺² + 2e
  Zinc oxides by losing two electrons
• Ans 3: 2: Fe⁺²➜ +1e
  Fe oxides by losing are electron

How are elements are arranged in 4th period ?

• Ans 1: In fourth period 18 elements are arranged in the ascending order of their atomic number

For what purpose is U-235 used ?

• Ans 1: The radioactive isotopes are used to generate electricity by carrying out controlled nuclear fission reaction in nuclear reactions e.g U-235 is bombarded with slow moving neutrons . The uranium breaks to produce Barium - 139 and Krypton - 94 and three neutrons . A large amount of energy is released which is used to convert water into steam boilers . The steam drives the turbine to generate electricity . This is the peaceful use of atomic energy

What happens at cathode in galvanic cell ?

• Ans 1: Reduction process takes place at cathode in galvanic cell
  Cu⁺² + 2e➜ Cu

Write electronic configuration of Neon and Berylium

• Ans 1: Atomic number of Neon 10
• Ans 2: ₁₀N = 1s² , 2s² , 2p⁶
• Ans 3: Atomic number ofBerylium is4
• Ans 4: ₄Be = 1s² , 2s²

State Charles's law

• Ans 1: The volume of a given mass of a gas is directly proportional to the absolute temperature when pressure kept constant."

Why solid show rapidly ?

• Ans 1: The particles of solids are fixed at their position and are not mobile . Therefore they have rigid structure and definite shape .

Write down names of any two moderate reactive metals

• Ans 1: 1: Magnesium
• Ans 2: 2: Silver

Why is BF³, electron deficient?

• Ans 1: In BF³ molecule, three valence electrons of boron atom pair up with three electrons, one from each of three fluorine atoms. the boron atom even after the sharing of electron, remain shortage of 2 electrons in its outer most shell

Write the names of noble metals .

• Ans 1:
  The metals which give least reactions are called noble metals
  
  

Why melting point and boiling points of ionic compounds are high?

• Ans 1: Melting and boiling of ionic compounds are high because thy consists of positive and negative ions . There exists very strong electrostatic interaction between these charged ions . That is why a lot of force is required to break these forces

Write two significance of chemical formula .

• Ans 1: 1: it indicates the mass of the compound in amu or grams
  
  
  
  
• Ans 2: 2: Chemical formula represents the name of the substance e.g H2O (Water)
• Ans 3: 3: It also represents one mole of the molecule in the balance chemical equation

How iron is prevented from rust by tin coating ?

• Ans 1: 1:It involves the dipping of the clean sheet of iron in a bath of molten tin and then passing it through hot rollers
• Ans 2: 2: Such sheets are used in the beverage and food cans
• Ans 3: 3: The tin protects the iron only long as its protective layer remains intact . Once it is broken and the iron is exposed to the air and water , a galvanic cell is established and iron rusts rapidly

Compare two physical properties of metals and non-metals .

• Ans 1: Metal :
  1:Almost all metals are solid (except mercury) they have high densities
• Ans 2: 2: After heating metals becomes soft and flexible
  3: Metals have ability to make positive ions by losing electrons

  Na➜ Na +1e
  4: They react with oxygen and produce basic oxides
  4Na +O₂➜2Na₂O
• Ans 3: Nin-metal :
  1: Solid non-metals are brittle
  2:They have low densities
• Ans 4: 3: Non-metals have ability to make negative ions by gaining of electrons
• Ans 5: 4: They react with oxygen and produce acidic oxides
  C+O₂➜CO₂
  S+O₂➜SO₂

Why shielding effect of electrons makes action formation easy ?

• Ans 1: As we move down in a group more and more shells come between valence shell and the nucleus of an atom , additional shell reduce the electrostatic force of attraction felt by the electron present in the outermost shell and the shielding effect increases resultantly , and electrons can be taken away , easily and cations form

Why suspensions and solutions do not show Tyndall effect , while colloids do ?

• Ans 1: Suspensions and solutions do not show Tyndall effect because particles of solution are so small that can't be scatter the rays of light and particles of suspension are so big that light is blocked and difficult to pass . The colloids do show Tyndall effect because particles scatter the path of light rays thus emitting the beam of light i-e exhibit the Tyndall effect

What is diffusion ? Explain with example .

• Ans 1: Diffusion : The process in which molecules more from the area of higher concentration move to the area of lower concentration until the state of equilibrium is achieved is called diffusion
• Ans 2: Example : If we open perfume bottle in the corner of the room , the fragrance of perfume spread in whole room by diffusion

Define electronic configuration . Also give example .

• Ans 1: The distribution of electrons around the nucleus in various shells and sub shells according to their increasing energy is called electronic configuration.
• Ans 2: Example : Electronic configuration of hydrogen is 1s¹

Write two uses of calcium .

• Ans 1: 1: It is used to remove sulphur from petroleum products
• Ans 2: 2: It is used as reducing agent to produce Cr, U and Zr

Identify strong or weak electrolyte among the following

CuSO₄ , H2CO₃ ,(OH)₂ , AGNO₃ , Ca (OH)₂

• Ans 1: Strong electrolyte :HCL,HNO₃ and CuSO₄. AgNO₃ are strong electrolyte
• Ans 2: Weak electrolyte: H2CO3. Ca (OH)₂ is weak electrolyte

Why is ionization energy of sodium is less than magnesium ?

• Ans 1: Ionization energy of sodium is less than that of magnesium ,because it becomes very difficult to remove second electron from Mg+ ions as nuclear charge attracts the remaining electrons more strongly . In the result of this attraction size of the ion decreases, So all the elements of alkaline earth metals have high ionization energies as compared to alkali metals

What are difference between string and weak electrolytes .

• Ans 1: Strong electrolyte : The substance which ionizes completely in solution to produce more ions which can conduct strongly is called strong electrolyte
• Ans 2: Example : NaCl , NaOH , H₂SO₄ etc
• Ans 3: Weak electrolyte : The electrolytes which produce less ions and mostly remained unionized in aqueous solution called weak electrolytes
• Ans 4: Example CH₃COOH (Acetic acid)

Differentiate between ionic bond and covalent bond .

• Ans 1: Ionic Bond :
  The type of chemical bond which is formed due to complete transfer of electron from one atom to another atom is called ionic bond
• Ans 2: Example :Na + Cl➜NaCl
• Ans 3: Covalent bond :The type of chemical bond which is formed due to mutual sharing of electrons is called covalent bond
• Ans 4: Example : H0 + xH➜H0xH

Calculate the value of angular momentum of 1st orbit where mvr = nh/2π

• Ans 1: Let angular momentum (mvr) of first orbit is =mvr = nh/2π
• Ans 2: By putting the values of h andπ
• Ans 3: mvr = 1x6.63x 10 ^-34
  ⁼ 1.0 x 10^-34kgm²s^-1

Write two uses of isotopes

• Ans 1: 1: In the field of medicine isotopes of iodine 131 are use for diagnose of goiter in thyroid gland
• Ans 2: 2: When the nucleus of U-235 breaks a large amount of energy is released which convert water into steam in boilers and produce electricity

What is atomic number of Sulphur ? Write down its electronic configuration .

• Ans 1: Atomic number of Sulphur IS 16 .
• Ans 2: S = 1s² , 2s² , 2p⁶ , 3s² , 3p⁴

How molar solution is prepared ?

• Ans 1: One molar solution is prepared by dissolving 1 mole of the solute in sufficient water to make the total volume of solution upto 1 dm³ in a measuring flask
• Ans 2: Example : 1 M solution of NaOH is prepared by dissolving 40g of NaOH in sufficient water to make the total , volume 1 dm³

Why benzene is insoluble in water ?

• Ans 1: The principle of solubility is 'like dissolve like' . Benzene is a non-polar compound whereas water is a polar compound . Due to the reason , benzene is insoluble in water

Do you know any element having no neutron in its atom ?

• Ans 1: Isotope of hydrogen , protium have one proton and no neutrons in it

What is Radical?

• Ans 1: An atom or a group of atoms that have some charge and keeps in contact during a chemical reaction is called a radical e.g. Hydronium and carbonate.

How many amu 1 g of a substance has ?

• Ans 1: 1.66x 10^-24g +1 amu
  1g = 1/1.66x 10^-24amu

In which form sulphur exists at I00°C?

• Ans 1: Sulphur exists in monoclinic form at 100"C because at room temperature sulphur exists in rhombic form. The transition temperature of sulphur is 96"C at which rhombic sulphur convened into monoclinic form.

Why do non-metals accept electron readily ?

• Ans 1:
  Non-metals have high electronegativity , can accept electrons readily in order to complete their last (valence ) shells
  
  

How many members are in group 17, is there any liquid, what is its name?

• Ans 1: There arc five members in group 17 which are F,C1 .Br , I and At. Only one liquid element is present named as bromine Br).

WHat do you know about the oxidizing characteristics of halogens ?

• Ans 1:
  Chlorine is the most poweful oxidizing agent. Oxidizing property of halogens is decreased from top to bottom . All halogens react with hydrogen gbas in the
  presence of light and catalyst to make halides . Stability of their hydrogen halides are given below
  HF > HCL > HBR > HI
  
  

What do you mean by horticulture and how it is related agriculture ?

• Ans 1: It deals with the art of gardening . A horticulture works fir the betterment of existing varieties and for the production of new varieties of ornamental plants and fruits plants

Wrote the observations made by Rutherford .

• Ans 1: Observations made by Rutherford are as follows :
• Ans 2: 1: Most of the alpha particles passed through the gold foil un-deflected
• Ans 3: 2: Out of 20,000 particles , only few were deflected at fairly large angles and very few bounced back on hitting the gold foil

How many blocks are present in periodic table ?

• Ans 1: There are4 presentin periodic table called s, p, d and f block

How are elements are arranged in 4th period ?

• Ans 1: In fourth period 18 elements are arranged in the ascending order of their atomic number

What type of elements form metallic bond?

• Ans 1: Metals form metallic bond

Give uses of platinum

• Ans 1:
  Uses of platinum :
  1: Platinum is used in hard disk coating and in maufacturing fibre optic cables
  
  
• Ans 2:
  2: Platinum is used in making jewellery .
  
  
• Ans 3: 3: Platinum is also used in making plastic of fiberglass and glass of LCD

Why are the rates of diffusion in liquids slower than that of gases?

• Ans 1: In liquid molecules intermolecular forces are stronger than gases and there molecules are, closer to each other. Asa result rate of diffusion in liquids are slower than gases.

Give electronic configuration of hydrogen ?

• Ans 1: Electronic configuration of ¹1H is 1s¹

What do you mean by 1 atom of C and 1 gram of atom of C ?

• Ans 1: One atom of carbon has its atomic mass which is 12 amu . But when this mass of carbon atom atom is expressed in grams then it is known as gram atomic mass . As 1 gram of carbon = 12.0 g

Define Triatomic molecule and polyatomic molecule

• Ans 1: Polyatomic molecule : The molecules which consists of many atoms calledpolyatomic molecule
• Ans 2: For example : C6H12O14 glucose N2H4 hydrazine
• Ans 3: Triatomic molecule: The molecules which consists of three atoms called
  triatomic molecule
• Ans 4: For example : H2O , CO2

Where sodium metal is obtained from fused sodium chloride .

• Ans 1: Sodium metal accumulates at iron cathode in down's cell

What is by-products are produced in Down's cell?

• Ans 1: Chlorine is produce in the downs cell as a by product

Define corrosion ?

• Ans 1: Corrosion is slow and continuous eating away a metal by the surrounding medium . It is a redox chemical reaction that takes place by the action of air and moisture with metals
• Ans 2: Example : The most common example of corrosion is rusting of ion

If an element has atomic number 13 and atomic mass 27 , how many electrons are there in each atom of the element?

• Ans 1: Atomic number of an element (Z) =13
  Mass no.of an atom (A) =27
  A the total number of electrons in an atom is equal to its atomic number (Z) ,so it will have 3s electrons

Why the second ionization energy of magnesium is higher than the first one?

• Ans 1: he l ionization energy of magnesium is high but the 2" ionization energy of magnesium i, very high. It becomes very difficult to remove second electron from the Mg' ion as nuclear charge attracts the remaining electrons strongly. As a result of this attraction size of the ion decreases.

Define formula mass and formula unit .

• Ans 1: Formula unit : formula unit is defined as the simplest whole number ratio of ions ,as present in the ionic compounds
• Ans 2: Example : Formula unit of common salt consists of one Na+ and one Cl- ion
• Ans 3: Formula mass:formula mass is the sum of atomic masses of all the atoms present in one formula unit of a substance
• Ans 4: Example : formula mass of sodium chloride is 58.5 amu

Write down names of two very reactive metals .

• Ans 1: 1: Li (Lithium)
• Ans 2: 2: Na (Sodium)

What type of covalent bond is formed in nitrogen molecule?

• Ans 1: In nitrogen molecule. three bond pairs are involved in bond formation. This type is called triple covalent bond. Three small lines are used to indicate these three pairs of electrons between those atoms in the molecules of such compounds.

Write down the position of hydrogen in the periodic table

• Ans 1: First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period

An element has 5 electron in M shell . Find out its atomic number ?

• Ans 1: The number of this element will be 15

How many members are in group 17, is there any liquid, what is its name?

• Ans 1: There arc five members in group 17 which are F,C1 .Br , I and At. Only one liquid element is present named as bromine Br).

Why is 2nd ionization energy of magnesium very high than its 1st ionization energy

• Ans 1: Second ionization energy of magnesium is very high than its first ionization energy . Because it becomes very difficult to remove second electron from the Mg- ions as the nuclear charge attracts the remaining electrons strongly

Why 2nd ionization energy of an elements is higher than first one?

• Ans 1: fins: energy required to remove an electron from isolated mono positive gaseous ion (M') is called second ionization energy. So more energy is required to remove second electron from a mono positive gaseous ion because there is more electrostatic force present between the nuclei and electron. M⁺➜M⁺²1e^-

What are application of inorganic chemistry.

• Ans 1: It has application is every aspect of chemical industry such as glass, cement, ceramics and metallurgy.

Why does 10 g nitrogen gas contain the same number of molecules as 10g of carbon monoxide ?

• Ans 1: Number of moles of nitrogen gas = 10/28 =0.35mol
  Number of molecules of N₂ = 0.35x0.22x10²³
  =2.107x10²³
• Ans 2: Number of moles of carbon monoxide gas = 10/28 = 0.35 mol
  
  
• Ans 3: Number of molecules of CO2 gas = 0.35x6.022x10²³
  = 2.107x10²³

Which are physical properties of matter ?

• Ans 1: 1: Matter exists in three physical state i-e gas, liquid , and solid
• Ans 2: 2: The simplest form of matter is the gaseous state
• Ans 3: 3: Liquids are less common and most of the matter exists as solid

Write two significance of chemical formula .

• Ans 1: 1: it indicates the mass of the compound in amu or grams
  
  
  
  
• Ans 2: 2: Chemical formula represents the name of the substance e.g H2O (Water)
• Ans 3: 3: It also represents one mole of the molecule in the balance chemical equation

What is difference between steel and stainless steel ?

• Ans 1: Steel : Alloy of iron with other metals called steel
• Ans 2:
  Stainless steel : Alloy of iron and chromium is called stainless steel
  
  

Why does sodium form a chemical bond with chlorine ?

• Ans 1: Sodium become Na by losing an electron and eight electrons remains in its valence shell . Chlorine gain an electron and becomes Cl^-ion . Both these ions attract each other and become stable
• Ans 2: Na + Cl➜NaCl

How many amu 1 g of a substance has ?

• Ans 1: 1.66x 10^-24g +1 amu
  1g = 1/1.66x 10^-24amu

Which variables are kept constant in Charles' law?

• Ans 1: Pressure is kept constant in Charles' law

An element X has oxidation state 0 . What will be the oxidation state when it gains three electrons ?

• Ans 1: Suppose the element x
  X0 +3e^-➜ X^-3

Differentiate duplet and octet rule.

• Ans 1:
  Duplet Rule:
  Attaining two electrons in valence called duplet rule.
  Example. , Li⁺Hefollow duplet rule.
• Ans 2:
  Octet Rule
  Attaining eight electrons in their valence shell is called octet rule
• Ans 3: Example : Ne ,Ar , Cl^-follow octet rule

Give the characteristics properties of ionic compounds

• Ans 1: the characteristic properties of ionic compounds. %Its: Characteristic Properties of Ionic Compounds: (I) lanai compounds are mostly crystalline solids. In I Ionic compounds in solid state have negligible electrical conductance but they are good conductors in solution and in the molten form. It is due to presence of free inns in them. lilt) Ionic compounds have high melting and boiling point example. NaCI has M.P. 800°C and B.P. 1413°C. (iv) Ionic compounds dissolves in polar solvents. Like NaCI dissolves in water.

In which pattern modern periodic table was arranged?

• Ans 1: According to increasing atomic number.

Which branch of chemistry deals with the structure and properties of naturally occurring molecules.

• Ans 1: "Organic chemistry deals with the structure and properties of naturally occuriring molecules."

What is difference between valency and oxidation ?

• Ans 1: Valency : Valency is the combining capacity of an atom with other atoms . It depends upon the number of electrons in the outermost shell
• Ans 2: 2: Valency is written as the sign followed by the number i-e 2 +
  Example :
  Valency of chlorine is 1
• Ans 3: Oxidation state :
  Oxidation state or oxidation number (O.N) is the apparent charge assigned to an atom of an element in a molecule or in an ion
• Ans 4: 2: Oxidation state is written as the sign precedes the number . It is written as +2
• Ans 5: Example In HCL , oxidation number of H is +1 and that of Cl -1

Define corrosion ?

• Ans 1: Corrosion is slow and continuous eating away a metal by the surrounding medium . It is a redox chemical reaction that takes place by the action of air and moisture with metals
• Ans 2: Example : The most common example of corrosion is rusting of ion

Explain the law of flow of heat ?

• Ans 1: In winter atmospheric temperature falls lower than that of our body temperature . According to principle of heat flow out from our body and we feel cold . To control this outward flow of heat , we wear black and warm clothes . To maintain body temperature we use dry fruits tea, coffee and meats etc

Why arc the densities of gases tower than that of liquids?

• Ans 1: Gases has e low density than liquids and solids. It is due to light mass and more volume occupied by the gas molecules.

Define ionization energy .

• Ans 1: Ionization energy is the minimum amount of energy required to remove the most loosely bound electron from the valence shell of an isolated gaseous atom

Calculate the oxidation number of Sulphur (S) in H₂SO₄

• Ans 1: H₂SO_{4 = 2(+1) +(S) +4(-2)}
  _=2=S-8
  _{S = +6}

Define formula mass and formula unit .

• Ans 1: Formula unit : formula unit is defined as the simplest whole number ratio of ions ,as present in the ionic compounds
• Ans 2: Example : Formula unit of common salt consists of one Na+ and one Cl- ion
• Ans 3: Formula mass:formula mass is the sum of atomic masses of all the atoms present in one formula unit of a substance
• Ans 4: Example : formula mass of sodium chloride is 58.5 amu

Why platinum is used as for making jewellery ?

• Ans 1:
  Platinum is very important metal . It is rust free and nin-reactive with oxygen and other gases which are present in atmosphere . Platinum is used to make .
  jewellery items because of its unique properties like colour , beauty , strenght , flexibilty and resistance to tarnish
  
  

What is meant by variable valency?

• Ans 1: Some elements show more than one combining power that is called variable valency for example, in Ferrous sulphate the valency of Iron is 2 whereas in ferric sulphate the valency of iron is 3

Which is most precious metal ?

• Ans 1: The most precious metal is platinum

How many amu 1 g of a substance has ?

• Ans 1: 1.66x 10^-24g +1 amu
  1g = 1/1.66x 10^-24amu

An element has 5 electrons in M shell . Find its atomic number

• Ans 1: The element has 5 electrons in M shell has atomic number 15 and name of element is phosphorous

Define element?

• Ans 1: Eelement:
  Eelement is define as the substance which is made up of atoms of the same type or a substance in which all the atoms have the same atomicnumber, e.g.
  Sodium (Na) and Hydrogen (H) etc

How many members are in group 17, is there any liquid, what is its name?

• Ans 1: There arc five members in group 17 which are F,C1 .Br , I and At. Only one liquid element is present named as bromine Br).

Define empirical formula and give an examples .

• Ans 1: Empirical formula: empirical formula is a formula which represents the simplest whole number ratio of atoms present in a compound
  
  
• Ans 2: Example : Empirical formula of benzene (C6H6) is CH .
  The Empirical formula of hydrogen peroxide (H2O2) is HO

How many sub shell are there in second sub shell ?

• Ans 1: In second sub shell 'L ' has two sub shells s and p
• Ans 2: L shell =s, p sub shell

For what purpose C-14 is used ?

• Ans 1: Uses of C-14
• Ans 2: 1: Age of old objects ( fossils ) can determined by ,measuring the radioactivity of C-14 in them
• Ans 3: 2: C-14 is used to label CO₂

Differentiate between donor atom and acceptor atom.

• Ans 1: Donor atom : The atom which donates the electron pair in coordinate covalent bond is called donor atom
• Ans 2: Acceptor atom : The atom which accepts the electron pair in coordinate covalent bond is called acceptor atom

What is difference between solution and mixture ?

• Ans 1: Solution : Homogenous mixture of two or more substance called solution
• Ans 2: Example : A solution of salt in water
• Ans 3: Mixture may be homogenous or heterogenous
• Ans 4: Example : Air is the mixture of many gases

What is atomic number of Sulphur ? Write down its electronic configuration .

• Ans 1: Atomic number of Sulphur IS 16 .
• Ans 2: S = 1s² , 2s² , 2p⁶ , 3s² , 3p⁴

How can you justify that air is a homogeneous mixture. Identify substances present in it?

• Ans 1: Air is a mixture formed by be the physical mixture of the substances like nitrogen, oxygen, carbon dioxide, noble gases and moisture and it has same composition throughout. So,it is homogenous mixture.

Why alkali metals are more reactive than alkaline earth metals ?

• Ans 1: Alkali metals are extremely reactive because of their ns¹valence shell electronic configuration . As there is only one electron in their valence shell , it can be easily given out . It is the reason that they are always found in in nature as cations with +1oxidation state . Therefore , they readily form salts with non-metals
• Ans 2: The alkaline earth metals are smaller and have more nuclear charge . They have two electrons in their valence shell i-e ns². They are also reactive but less than alkali metals

What happens at cathode in galvanic cell ?

• Ans 1: Reduction process takes place at cathode in galvanic cell
  Cu⁺² + 2e➜ Cu

Why is melting point of a solid considered its 'identification' characteristics ?

• Ans 1: The melting point of a solid considered its identification because pure solids have a sharp and specific melting point , no other solid has same melting point

Write difference between homoatomic and heteroatomic molecules ?

• Ans 1: Heteroatomic molecules:
  The molecules consisting of different types of atoms are called heteroatomic molecules
• Ans 2: Example: H2SO4, SiO2 , HCl etc
• Ans 3: Homoatomicmolecules:
  The molecules consisting of same types of atoms are called heteroatomic molecules
  
• Ans 4: Example : H2 ,O2,O3,S8 etc

Write two significance of chemical formula .

• Ans 1: 1: it indicates the mass of the compound in amu or grams
  
  
  
  
• Ans 2: 2: Chemical formula represents the name of the substance e.g H2O (Water)
• Ans 3: 3: It also represents one mole of the molecule in the balance chemical equation

What is difference between solution and mixture ?

• Ans 1: Solution : Homogenous mixture of two or more substance called solution
• Ans 2: Example : A solution of salt in water
• Ans 3: Mixture may be homogenous or heterogenous
• Ans 4: Example : Air is the mixture of many gases

Define Biochemistry.

• Ans 1: "It is branch of chemistry in which we study the structure, composition and chemical reactions of substances found in living organisms .

^{Why magnesium is harder than sodium?}

• Ans 1: Magnesium is harder than sodium because in magnesium metallic bonding is stronger. While sodium is relatively soft metal due to weak metallic bonding in their atoms.

What would be the number of moles in 9.0 gram carbon ?

• Ans 1: Number of moles of carbon = 9 g
  Molar mass of carbon = 12 g
  Number of moles = ?
  
  
• Ans 2: Number of moles = mass of thing / molar mass of thing
  = 9/12
  = 0.75

Which are physical properties of matter ?

• Ans 1: 1: Matter exists in three physical state i-e gas, liquid , and solid
• Ans 2: 2: The simplest form of matter is the gaseous state
• Ans 3: 3: Liquids are less common and most of the matter exists as solid

Can pure gold be used for making ornaments ? If not , why ?

• Ans 1: Gold is too soft ,to be used as such . That is why it cannot be used aline in making ornaments . It is always alloyed with copper ,silver or some other metals

An element has an atomic number 17 , how many electrons are present in K and M shells of an atom ?

• Ans 1: K=2 , L= 8 , M=7
  An atom has atomic number 17, in first shell (K) contains 2 electrons , then second shell called (L) shell have 8 electron and 3rd shell (M) have 7 electrons

Define Mendeleev's periodic table ?

• Ans 1: A Russian chemist arranged elements (63) discovered at that time according to increasing atomic mass . ' Properties of elements are periodic function of their atomic masses '

Write uses of silver .

• Ans 1:
  1: Being very sift metal , it is rarely used as such . Alloys of silver woth copper are widely used in making coins , silver-ware and ornaments
  2: Compiunds of silver are widely used in photographic films and dental preparations
  3: Silver also has important applications in mirror industry
  
  

What is meant by dipole dipole forces of attraction ?

• Ans 1: When partial positive and partial negative charges exists at different positions in a molecule , the adjacent molecules will arrange themselves in such a way that negative end of that molecule comes near to positive end of other molecule . It results in a net forces of attraction between oppositely charged ends of two adjacent molecules . These attractive forces are called dipole - dipole forces

Define aqueous solution . Write its components .

• Ans 1: The solution which is formed by dissolving substance in water is called an aqueous solution . Water in the solution always in large amount and are called solvents
• Ans 2: Example : Salt in water or sugar in water are two examples of aqueous solution

Why an iron grill is painted frequently?

• Ans 1: Iron grill is painted frequently because due to presence of oxygen and water in air. It become, corrode. So to prevent it front rusting it is painted

iodine exists in solid state, can it be beaten with hammer to form sheets?

• Ans 1: No, only solid metals have the characteristic to be beaten with hammer to for sheet

Which compounds of halogens are stable ?

• Ans 1: Halogens form very stable compounds with alkali metals

What is electronegativity ? Write its unit .

• Ans 1: The ability of an atom to attract the shared pair of electrons towards itself in a molecule is called electronegativity
• Ans 2: For example :
  Electronegativity of nitrogen = 3.0
  
  Electronegativity of Oxygen = 3.4
  
  Electronegativity of Fluorine = 4
  

Why calcium is more electropositive than to magnesium?

• Ans 1: Calcium is more Electropositivity than magnesium because metallic character or electroposltve character or electropositive character down the group increases due to loosely held and can be easily with drawn from their shells.

Explain any two factors that effect the diffusion .

• Ans 1: Factors effecting in diffusion :
  1 :Size of molecules : Big sized molecules diffuse slowly
• Ans 2: 2: Intermolecular forces : The molecules having weak intermolecular forces diffuse faster than those having strong intermolecular forces

Why does oxygen molecule not form a polar covalent bond ?

• Ans 1: In oxygen molecule formed by hydrogen and oxygen and hence there will be electronegativity difference between the oxygen and hydrogen . Due to which oxygen atlain negative and hydrogen atlain positive charge

Differentiate between atom and ion ?

• Ans 1: Atom :
  1: It is the smallest particle of an element
  2: It can or cannot exists independently and can take part in a chemical reaction
  3: It is electrically neutral
• Ans 2: Ion:
  1: It is the smallest unit of an ionic compound
  2: It cannot exists independently and is surrounded by oppositely charged ions

How do atoms follow octet rule?

• Ans 1: Atoms follow octet rule to have the noble gas electronic configuration. For this purpose atoms attain 8 electrons in the outermost shell either by sharing. by losing or by gaining electrons

Define oxidizing and reducing agents with example .

• Ans 1: Oxidizing agent:
  1: Oxidizing agent is the species that oxides a substance by taking electrons from it
  2: The substance (atom or ion ) which is reduced itself by gaining electrons is also called oxidizing agent
  
  
• Ans 2: Example : Nin-metals are oxidizing agents because they accept electrons being more electronegative elements
• Ans 3: Reducing agent :
  1: Reducing agent is the specie that reduces a substance by donating electron to it
  2: The substance (atom or ion ) which is oxidized by losing electrons is also called reducing agent
• Ans 4: Example : Almost all metals are good reducing agents because they have the tendency to loose electrons

Write down the chemical formulas of the following

(a) Sugar (b) Sulphuric acid

• Ans 1: (a) Sugar : C12H22O11
• Ans 2: (b) Sulphuric acid : H2SO4

how can you explain the solute-solvent interaction to prepare NaCI Solution?

• Ans 1: When NaCI is added in water it dissolves readily because the attractive interaction between the ions of NaCI and polar molecules of water are strong enough to overcome the attractive forces between Na' and CI- ions in solid NaC1 crystal. In this process the positive end of the water dipole is oriented towards the CF ions and the negative end of water dipole is orwater molecules are so strong that they pull these ions from their positions in the the Na- ions. These ion dipole attractions between Na+ ions and water molecules, Cl- ions and water molecules are so strong that they pull these ions from their positions in the crystal and thus NaCl dissloves

Write two examples of gas into gas solution .

• Ans 1: 1:Air
  
• Ans 2: 2: Mixture of H₂ and He in wheather ballons
• Ans 3: 3: Mixture of N2 and O2 in clinders for respiration

In which form sulphur exists at I00°C?

• Ans 1: Sulphur exists in monoclinic form at 100"C because at room temperature sulphur exists in rhombic form. The transition temperature of sulphur is 96"C at which rhombic sulphur convened into monoclinic form.

Write four examples of mixture .

• Ans 1: 1: Air is a mixture of nitrogen , carbon dioxide , noble gasses and water vapours
• Ans 2: 2: Solid us a mixture of sand , clay , mineral salts , water and air
• Ans 3: 3: Milk is a mixture of water , sugar k, fat , proteins , minerals , salts and vitamins
• Ans 4: 4: Brass is a a mixture of copper and zinc metals

What is the empirical formula of acetic acid ? Calculate its molecular mass.

• Ans 1: Empirical formula of acetic acid CH2O
• Ans 2: Molecular mass of acetic acid:
• Ans 3: CH3COOH=2(12)+4(1)+16(2)
  =24+4+32
  =60a.m.u

Why solid show rapidly ?

• Ans 1: The particles of solids are fixed at their position and are not mobile . Therefore they have rigid structure and definite shape .

What is difference between ion and free radical ?

• Ans 1: Free radicals :
  1: These are the atoms that have odd number of electrons . They do not have any charge
  2: They can exists in solutions as well as in air
  3: They may form in the presence of light
• Ans 2: Ion
  1:These are the atoms which bear some charge
  2: They can exists in solutions or in crystal lattice
  3: Their formation is not affected by the presence of light

Magnesium has electronic configuration 2,8,2

a: How many electrons are in outermost shell ?

b: In which sub-shell of outermost shell electrons are present ?

c: Why magnesium tends to lose electron ?

• Ans 1: a: There are two electrons in outermost shell
  b : In sub-shell of outermost shell electron are present
  1s² , 2s² , 2p⁶ .3s²
• Ans 2: c: Because Mg is an electropositive element having tendency to lose electron .So it loses its outermost 2 electrons and became MG ⁺²

Why the elements are called s and p block elements?

• Ans 1: The elements having their valence electrons in s and p sub shell called s and p blocks elements.

How is platinum used as a catalyst in automobiles and what are advantages of this use?

• Ans 1: An alloy of platinum. palladium and rhodium is used as catalyst in automobiles as catalytic converter. It converts most of the toxic gases (CO, NO2) being emitted by vehicles into less harmful carbon dioxide. nitrogen and water vapour.

Describe at least two necessary conditions for the formation of covalent bond .

• Ans 1: 1: A covalent bond is formed between two non-metals
• Ans 2: 2: Electronegativity difference between combining atoms of non-metals must be very low
• Ans 3: 3: The two combining atoms should have high ionization energy

What is matter ? How many states it has ?

• Ans 1: Matter is any thing that has mass and occupies space .
• Ans 2: State of matter :
  1: Solid
• Ans 3: 2: Liquid
• Ans 4: 3: Gas

Write two physical properties of magnesium .

• Ans 1: Magnesium is good conductor of heat and electricity
• Ans 2: Sodium reacts with oxygen to form sodium oxide .
• Ans 3: 4Na +O₂➜ 2Na₂O

Differentiate saturated and unsaturated solution

• Ans 1: Saturated : A solution containing maximum amount of solute at a given temperature is called saturated solution
• Ans 2: Unsaturated : A solution which contains lesser amount than that which is required to saturate it at given temperature is called unsaturated solution

How was it is proved that whole mass of an atom is located at its center ?

• Ans 1: The complete rebounce of a few particles show that the nucleus is very hard , dense and contain all mass of an atom

Why the electrons move freely in metals ?

• Ans 1: This is because the valence shell electrons loosely held by nucleus of an atom . There is the weak force of attraction present between nucleus and the mobile valence electrons . Therefore valence electrons move freely in metals

Define noble gases and give example .

• Ans 1: Elements of group 18 are called Noble gases
  All noble gases have completely filled outermost shells . This is because of this reason , they do not sow any chemical reactivity . They are chemically inert
• Ans 2: Example : Helium , Neon , Argon etc

Which form of Sulphur exists at room temperature?

• Ans 1: Rhombic (S₈) Sulphur exists at room temperature

Complete the following chemical equation .

• Ans 1: NaO +H₂O➜ 2NaOH
• Ans 2: MgO+ H₂O➜ Mg (OH)₂

Can, you cool a gas by increasing its volume

• Ans 1: No. we cannot cool a gas by increasing its volume

What is meant by atomic radius ? What is its unit ?

• Ans 1: The half of the distance between the nuclei of two of similar adjacent (bonded) atoms is called atomic radius
• Ans 2: Its unit is pico meter (pm)

What is metallic coating ?

• Ans 1: For the protection against the rusting metals are coated with other metal and it is called metallic coating.

Which of the following will scatter light and why?

Sugar solution, Soap solution, Milk of magnesia.

• Ans 1: Soap solution is colloidal solution and have particles large enough to scatter the light

Write the simplest way to distinguish between solution and pure liquid .

• Ans 1: The simplest way to distinguish between a solution and a pure liquid is evaporation . The liquid which evaporates completely , leaving no residue , is a pure compound , while a liquid which leaves behind a residue on evaporation is solution

Write the names of noble metals .

• Ans 1:
  The metals which give least reactions are called noble metals
  
  

Explain why are oxygen and hydrogen considered elements whereas water as a compound ?

• Ans 1: Hydrogen and oxygen are element because
  1: Each one of it consists of same type of atoms
  
  
• Ans 2: 2: Each of it has same atomic number
• Ans 3: Water is a compound because :
  1: It consists of different types of atoms combined together in a fixed proportion by mass
  2: Properties of water are entirely different from its constituent components For example : water exists as liquid while hydrogen and oxygen exists as gases at room temperature

Is the Boyle's law valid at very high temperature?

• Ans 1: No. Boyle's law is not valid at very high temperature

Write down the position of hydrogen in the periodic table

• Ans 1: First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period

Why arc the densities of gases tower than that of liquids?

• Ans 1: Gases has e low density than liquids and solids. It is due to light mass and more volume occupied by the gas molecules.

What happens to iron in the rusting process ?

• Ans 1: The oxidation of iron take place during rusting process and forms Fe₂O₃ . The chemical formula of rust is Fe₂O₃nH₂O

Why the second ionization energy of magnesium is higher than than first ?

• Ans 1: Second ionization energy of magnesium is higher than than first , because it is very difficult to remove the second electron from the Mg⁺ ion due to much nuclear attraction . As a result of this attraction , size of ions decreases . Due to this reason , the second ionization energy of magnesium is higher than the first

Define Empirical formula and give examples.

• Ans 1: "It is the simplest whole number ratio of atoms present in a compound" Example: Empirical formula of benzene(C6H6) is CH Empirical formula of Hydrogen peroxide (H2O2) is HO

How many blocks are present in periodic table ?

• Ans 1: There are4 presentin periodic table called s, p, d and f block

In which branch of chemistry deals with preparation of paints and papers?

• Ans 1: "Industrial chemistry deals with preparation of paints and papers".

how can you explain the solute-solvent interaction to prepare NaCI Solution?

• Ans 1: When NaCI is added in water it dissolves readily because the attractive interaction between the ions of NaCI and polar molecules of water are strong enough to overcome the attractive forces between Na' and CI- ions in solid NaC1 crystal. In this process the positive end of the water dipole is oriented towards the CF ions and the negative end of water dipole is orwater molecules are so strong that they pull these ions from their positions in the the Na- ions. These ion dipole attractions between Na+ ions and water molecules, Cl- ions and water molecules are so strong that they pull these ions from their positions in the crystal and thus NaCl dissloves

Differentiate between molecular mass and formula mass, which of the following will be molecular formula?

• Ans 1: H₂O,NaCl, KI, H₂SO₄

How many atoms are present in 16 g of O and 8g of S?

• Ans 1: 16 grams of oxygen has 6.022 x 10²³atoms and 8 grams of sulphur has 1.055x10²³atoms.

What is meant by metallic bond ?

• Ans 1: When positively charged metal ions are held together by freely moving electrons , the bond which is formed called metallic bond

Write down atomic number of nitrogen and oxygen .

• Ans 1: The atomic no of N₂ is = 7
• Ans 2: Electronic configuration of ₇N = 1s² , 2s² , 2p³
  ^{The atomic no of 0}₂is =8
• Ans 3: Electronic configuration of ₈O = 1s² , 2s² , 2p⁴

Write two physical properties of non-metals.

• Ans 1:
  1: Non-metals have less melting and boiling point (except diamond)
  2: They are generally soft (except diamond)
  
  

What are anode or cathode ?

• Ans 1: Anode : It is the electrode at which the oxidation takes place
• Ans 2: Cathode : It is the electrode at which the reduction takes place

What elements do the following compound contains ?

• Ans 1: Sugar ,common salt , lime water and chalk
• Ans 2: Glucose :It contains carbon, hydrogen , and oxygen (C₆H₁₂O₆)
• Ans 3: Common salt : It contains sodium , and chlorine (NaCl)
• Ans 4: Lime water : It contains calcium ,oxygen , and hydrogen Ca (OH)₂
• Ans 5: Chalk : It contains calcium ,carbon, and oxygen CaCO₃

Describe trend of shielding effect in periodic table .

• Ans 1: The shielding effect increase down the group in the periodic table . Because of this it is easy to take away electron in potassium (Z=19) than from sodium (Z=11) atoms . Similarly the shielding effect decrease in a period if we move from left to right

Define super-saturated solution .

• Ans 1: The solution that is more concentrated than a saturated solution at a given temperature is known as super- saturated solution

Describe difference between Rutherford's theory and Bohr's atomic theory .

• Ans 1: Rutherford's atomic theory
  1: It was based upon classical theory
  2: Electrons revolve around the nucleus
  3: Atoms should produce continuous spectrum
  4: Atoms should collapse
• Ans 2: Bohr's atomic theory
  1: It was based upon quantum theory
  2: Electrons revolve around the nucleus in orbit of fixed energy
  3: Atoms should produce line spectrum
  4: Atoms should exists

What are Dobereiner's triads ?

• Ans 1: A German chemist Dobereiner's observed relationship between atomic masses of several groups of three elements called triads . In triads the central and middle element had atomic mass average of the other two elements

Write the names of noble metals .

• Ans 1:
  The metals which give least reactions are called noble metals
  
  

Which is most precious metal ?

• Ans 1: The most precious metal is platinum

What is the electronegativity of hydrogen and chlorine ?

• Ans 1: 1: Value of electronegativity of hydrogen (H) is 22
• Ans 2: 2: Value of electronegativity of chlorine (Cl) is 3.2

Define Bond pair ?

• Ans 1: The valence electrons which take part in covalent bond is called bonding electrons . These electrons present in the incomplete valence shell

If an element has atomic number 13 and atomic mass 27 , how many electrons are there in each atom of the element?

• Ans 1: Atomic number of an element (Z) =13
  Mass no.of an atom (A) =27
  A the total number of electrons in an atom is equal to its atomic number (Z) ,so it will have 3s electrons

How can you differentiate between organic and inorganic chemistry .

• Ans 1: Organic chemistry : It is the study of the properties and behavior of hydrocarbons (compounds of carbon and hydrogen ) and their derivatives
• Ans 2: Inorganic chemistry : It is the study of the properties and behavior of all elements except the hydrocarbons and their derivatives

Anode of downs cell is made up of non metal , what is its name ?

• Ans 1: Anode of down cell is made of non-metal , Its name is graphite . The Cl^- ions are oxidized to give Cl₂ gas at anode

What is meant by variable valency?

• Ans 1: Some elements show more than one combining power that is called variable valency for example, in Ferrous sulphate the valency of Iron is 2 whereas in ferric sulphate the valency of iron is 3

What is relationship between Empirical formula and Molecular formula ?

• Ans 1: The relationship between Empirical formula and Molecular formulais given as
  Molecular formula = (Empirical formula)*n
  When n = 1,2 ,3 and so on
  

  
  
• Ans 2: Example:
  Molecular formula of benzene =C6H6 which is derived from the empirical formula CH when value of n = 6

Write any two rules for assigning oxidation number .

• Ans 1: 1: The oxidation number (O.N) of an ion consisting on a single element is the same as the charge on that ion .
• Ans 2: 2: In any substance the more electronegative atom has the negative O.N
• Ans 3: 3: In a neutral molecule , the sum of the O.N of all the elements is zero
• Ans 4: 4: The sum of O.N in ion is equal to the charge present on ions

A long as electron remains in an orbit , it does not emit or absorb energy , when does it emit or absorb energy ?

• Ans 1: When an electron jumps from lower orbit to higher orbit . It absorbs energy and when it jumps from higher orbit to lower orbit . It radiates energy . This change in energy ,

  △E given by following Plank's equation

• Ans 2:

  △E =E2-E1=hv where h is a plank's constant equal to 6.63x10-34Js and π is frequency of light

Convert 560 torr into cmHg

• Ans 1: 1 torr = 1mm Hg
• Ans 2: 1mm = 1cm/10
  1 torr = 1/10cmHg
• Ans 3: 560 torr = 1/10 cmhg x 560
  = 56 cm Hg

Define modern periodic law ?

• Ans 1: In 1913 H.Moseley given Modern law
  Properties of elements are periodic function of their atomic masses

What is the nature of electrode used in electroplating chromium ?

• Ans 1: During electroplating chromium the object to be electroplated act as cathode with anode is made up of antiamonial lead

Write the simplest way to distinguish between solution and pure liquid .

• Ans 1: The simplest way to distinguish between a solution and a pure liquid is evaporation . The liquid which evaporates completely , leaving no residue , is a pure compound , while a liquid which leaves behind a residue on evaporation is solution

Electronic configuration of Cl^- ion

• Ans 1: Cl^-1s² ,2s²,2p⁶ ,3s² ,3p⁶

Why does sodium form a chemical bond with chlorine ?

• Ans 1: Sodium become Na by losing an electron and eight electrons remains in its valence shell . Chlorine gain an electron and becomes Cl^-ion . Both these ions attract each other and become stable
• Ans 2: Na + Cl➜NaCl

What is difference between short period and ling period ?

• Ans 1: Short period : First period of periodic table is called short period . It consists of Hydrogen and Helium

Define empirical formula and give examples.

• Ans 1: It is the simplest whole number , ratio of atoms present in a compound." Empirical formula of benzene Empirical formula of Hydrogen peroxide

How many sub-shells are there in second shells ?

• Ans 1: Two sub-shells s and p are present in second shell L

Why silver and gold are least reactive ?

• Ans 1:
  From the transition metals of group 11 of periodic table Silover and Gold are least reactive because they do not lose electron easily
  
  

What are two defects in Rutherford's atomic model ?

• Ans 1: 1: According to classical theory of radiation , electrons being the charged particles should release or emit energy continuously and they should ultimately fall into the nucleus
• Ans 2: 2: If the electrons emit energy continuously, they should form a continuous spectrum but in fact , line spectrum was observed

How many atoms are present in one gram atomic mass of a substance?

• Ans 1: One gram atomic mass of a substance is equal to Avogadro's number in which 6.023 x 1023 atoms are present

Why the elements of group 13 to group 18 are called P block elements ?

• Ans 1: Elements of group 13 to 18 have their valence electrons in P subshell . Therefore , they are called as P-block elements

Name a metal which can be cut with knife?

• Ans 1: Sodium is that metal which can be cut with knife, because it is soft.

When do electrons emit or absorb energy ?

• Ans 1: A long as electron remain in a particular orbit it does not radiate or absorb energy, The energy is emitted or absorbed only when an electron jumps from one orbit to another

Why the boiling point of water higher than alcohol?

• Ans 1: Water has ability to form two hydrogen bonds while Ethyle alcohol has ability to form one hydrogen bond . That's why the boiling point of water is higher than alcohol

Give chemical reaction of methane with chlorine in bright light .

• Ans 1:
  In bright light (sun light) Cl2 react with CH4 violently and explosively
  Chemical reaction : CH4 +2Cl2 ➜ C+4HCL

What type of solution fog and brass are?

• Ans 1: 1: Fog is a solution of liquid solute in gas solvent
• Ans 2: 2: Brass is a solution of solid solute in solid solvent

What are elements in group 3 to 12 called ?elements are normal elements because their valence electrons lie in s and p sub shell

• Ans 1: Elements in group 3 to 12 elements are normal elements because their valence electrons lie in s and p sub shell

What is difference between elements and compound ?

• Ans 1: Compound : Compound is a substance made up of two or more elements chemically combined together in a fixed ratio by mass
  Example : Water (H2O)
• Ans 2: Element : Element is the substance made up of same type of atom , having same atomic number and cannot be decomposed into simple substance by chemical ways
  Example : Sodium : (Na) Copper : (Cu)

Why solution is considered mixture ?

• Ans 1: The chemical reaction did not take place between the components of solution and the components kept constant their properties . That's way solution is considered mixture .

Write two properties of gases

• Ans 1: 1: Molecules of gases are always in state of continuous motion . They have very high K.E .
• Ans 2: 2: Gases have very low density therefore , they have large volume

WHat do you know about the oxidizing characteristics of halogens ?

• Ans 1:
  Chlorine is the most poweful oxidizing agent. Oxidizing property of halogens is decreased from top to bottom . All halogens react with hydrogen gbas in the
  presence of light and catalyst to make halides . Stability of their hydrogen halides are given below
  HF > HCL > HBR > HI
  
  

Why the 2nd ionization energy is greater than 1st ionization energy ?

• Ans 1: Because after the removal of the first electron from the atom , its number of protons , become greater than electrons . The force of attraction between the nucleus and remaining valence shell electron increases . So more energy is required to remove the 2nd electron from the atom

In which form sulphur exists at I00°C?

• Ans 1: Sulphur exists in monoclinic form at 100"C because at room temperature sulphur exists in rhombic form. The transition temperature of sulphur is 96"C at which rhombic sulphur convened into monoclinic form.

What is the capacity of the K,L,M,N shells ?

• Ans 1: K shell can accommodate 2 electron
  L shell can accommodate 8 electrons
  M shell can accommodate 18 electrons
  N shell accommodate 32 electrons

Define reduction .

• Ans 1: Reduction is defined as addition of hydrogen or removal of oxygen during a chemical reaction
• Ans 2: Addition of hydrogen :
• Ans 3: H₂S +Cl₂➜ S+2HCL
• Ans 4: Removal of oxygen : 2Zn + CO₂

What is difference between group and period ?

• Ans 1: Group : The vertical columns present in periodic table are called groups .There are 18 groups present in the periodic table
• Ans 2: Period: The horizontal rows present in periodic table are called period .There are 7 periods present in the periodic table

Identify the following as empirical or molecular formula :

H₂O₂ ,CH₄ , C₆H₁₂O₆ , C₁₂H₂₂O₁₁ ,BaCO₃ ,KBr

• Ans 1: Empirical formula : KBr , BaCO_{3 ,} CH₄
• Ans 2: Molecular formula : H₂O_{2 ,}C₆H₁₂O_{6 ,}C₁₂H₂₂O₁₁

What is the relationship between electro positivity and ionization energy ?

• Ans 1: Electronegativity depends upon the ionization energy which is in turn depends upon size and nuclear charge of the atom
• Ans 2: 1: Small sized atom with high nuclear charge have high ionization energy
• Ans 3: 2:Atoms having high ionization energy are less electropositive or metallic

Why ionic compounds easily dissolve in water?

• Ans 1: They dissolve easily in water because water is a polar solvent and has high dielectric constant that weakens the attraction between ions.

Write down the electronic configuration of fluorine and Neon

• Ans 1: Electronic configuration of fluorine:
  ₉F=1s² , 2s² , 2p⁴
• Ans 2: Electronic configuration of Neon :
  ₁₀Ne = 1s² , 2s² , 2p⁶

Define pressure and write its unit .

• Ans 1: Pressure : It is defined as the force exerted by per unit surface area
• Ans 2: Formula :P = F / A
• Ans 3: Unit : Pressure has SI unit of Nm^-2It is also called pascal (Pa)

Difference between homogeneous and heterogeneous mixture.

• Ans 1: Homogeneous mixture: Mixtures that have uniform composition throughout are called homogeneous mixtures.
  example: Milm, Brass, Ice-cream.
• Ans 2: heterogeneous mixture: Mixture which does not have uniform composition throughout is called heterogeneous mixtures.
  example: Soil,Wood

Complete and balance the following equation Mg +N₂➜ ?

• Ans 1: 3Mg +N₂➜ Mg₃N₂
  _{(Magnesium ) (Nitrogen) (Magnesium nitride)}

Where sodium metal is obtained from fused sodium chloride .

• Ans 1: Sodium metal accumulates at iron cathode in down's cell

How will you test whenever given solution is colloidal solution or not?

• Ans 1: If the panicles scatter the path of light rays thus emitting the beam of light i.e exhibit the Tyndall effect than the given solution is colloid.

Write short note on discovery of Neutron.

• Ans 1: Chadwick discovered Neutrons in 1932 . He bombarded alpha particles on Beryllium . He observed that the radiation of very high penetrating power were produced ( They can move through long distance in air ) .These radiations were called Neutron

Give the electronic configuration of carbon atom.

• Ans 1: Atomic no. of carbon = Z= 6
  No of electrons in carbon atom =Z=6
  Electronic configuration of carbon atom=ls².2s²,2p²

Why test tube becomes cold when KNO3 is dissolved in water ?

• Ans 1: The dissolution of KNO₃ in water is an endothermic process in which heat absorbed when KNO₃ dissolve in test tube it becomes cold

Define hydrogen bonding ?

• Ans 1: Th partially positive charged hydrogen atom of one molecule attracts and forms a bond with partially negatively charged atom of the other molecule the bonding is called hydrogen bonding

Name a metal which exists in liquid form? Ans: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state

• Ans 1: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state

Write down names of any two moderate reactive metals

• Ans 1: 1: Magnesium
• Ans 2: 2: Silver

For an element Z = 92 A = 238 Calculate number of neutron in it

• Ans 1: Atomic mass = No of protons + No of neutrons =A=238
  No of protons Z = 92
  
  No of neutrons =N=A-z
  =238-92= 146

Write chemical reaction of H₂ with F2 and Cl₂ .

• Ans 1: Reaction of H₂ with F₂: Flourine combines with hydrogen even in the dark and cold state
  H2 +F2➜ 2HF
• Ans 2: Reaction of H₂withCl₂ : Chlorine reacts with hydrogen only in the presence of sunlight
  
  
  H2 +Cl2➜ 2HCL

Write formulas of two ionic compounds which are soluble in water .

• Ans 1: The two ionic compound which are soluble in water are following
• Ans 2: Sodium chloride : NaCl
• Ans 3: Sodium Thiosulphate : Na₂S₂O₃

What is meant by variable valency?

• Ans 1: Some elements show more than one combining power that is called variable valency for example, in Ferrous sulphate the valency of Iron is 2 whereas in ferric sulphate the valency of iron is 3

Write any two applications of inorganic chemistry.

• Ans 1: Inorganic chemistry has applications in following aspects of the chemistry industry
• Ans 2: 1: Glass industry
• Ans 3: 2: Cement industry
• Ans 4: 3: Ceram[ics and metallurgy

Why is 2nd ionization energy of magnesium very high than its 1st ionization energy

• Ans 1: Second ionization energy of magnesium is very high than its first ionization energy . Because it becomes very difficult to remove second electron from the Mg- ions as the nuclear charge attracts the remaining electrons strongly

Justify with an example the solubility of salt increases with increase in temperature?

• Ans 1: When salts like KNO3, KCl are added in water, the test tube become cold. It means during dissolution of this salts heat is absorbed. Such dissolving process in called endothermic Solvent + Solute + Heat-+Solution Solubility increase with the increase in temperature. It means that heat is required to break attractive forces b/w the ions of solute. This requirement is fulfilled by surrounding molecules.

Write electronic configuration of Sulphur .

• Ans 1: Electronic configuration of Sulphur :
• Ans 2: ₁₆S = 1S² , 2S² , 2P⁶ , 3S² , 3P⁴

Why are dipole forces of attraction not found in halogen molecules?

• Ans 1: Dipole forces of attraction do not found in halogen molecules because they have same electronegativity and there is equal sharing of electrons.

Why volume of gas decreases with increase of pressure ?

• Ans 1: Volume of gas decreases with increase of pressure because of empty spaces between their molecules . When gases are compressed the molecules come closer to one another and occupy less volume as compared to the volume in uncompressed state .

Why ionization energy ok alkaline earth metals is higher than alkali metals?

• Ans 1:
  The size of alkali metals is samaller than alkaline earth metals that's why they have high ionization energy
  
  

Give the composition of Earth Crust with respect to three major elements.

• Ans 1: Earth Crust is formed by three major elements having following percentages. Oxygen 47% Silicon 28% Aluminum 7.8%

Define brine ?

• Ans 1: The by-product in Nelson's cell are hydrogen gas (H₂) and chlorine gas (Cl₂)

What is diffusion ? Explain with example .

• Ans 1: Diffusion : The process in which molecules more from the area of higher concentration move to the area of lower concentration until the state of equilibrium is achieved is called diffusion
• Ans 2: Example : If we open perfume bottle in the corner of the room , the fragrance of perfume spread in whole room by diffusion

Why HF is a weak acid ?

• Ans 1: HF is a weak acid because in HF -compound . There is strong intermolecular bonding . So, it does not readily ionize in water and release H+ in water the strong acid is that which is readily ionized in water but HF does not easily ionized in water

What is maximum capacity of a metal ?

• Ans 1: 1: K shall can accommodate 2 electrons
• Ans 2: 2: L shall can accommodate 8 electrons
• Ans 3: 3: M shall can accommodate 18 electrons
• Ans 4: 4: N shall can accommodate 32 electrons
• Ans 5: O shall can accommodate 50 electrons

What happens to iron in the rusting process ?

• Ans 1: The oxidation of iron take place during rusting process and forms Fe₂O₃ . The chemical formula of rust is Fe₂O₃nH₂O

What is meant by variable valency?

• Ans 1: Some elements show more than one combining power that is called variable valency for example, in Ferrous sulphate the valency of Iron is 2 whereas in ferric sulphate the valency of iron is 3

Define alloy and give example .

• Ans 1: Alloy : alloy is a homogeneous mixture of one metal with one or more metals or non-metals
• Ans 2: Example : The best example of alloy is 'stainless steel'

Write name of any two elements found in gaseous state

• Ans 1: Nitrogen and oxygen both found in gaseous state

Why is galvanizing done?

• Ans 1: The process of coating a thin layer of zinc or iron is called galvanizing. Galvanizing is dot, because zinc protects the iron against corrosion even after the coating surface is broken.

What is by-products are produced in Down's cell?

• Ans 1: Chlorine is produce in the downs cell as a by product

What are Dobereiner's triads ?

• Ans 1: A German chemist Dobereiner's observed relationship between atomic masses of several groups of three elements called triads . In triads the central and middle element had atomic mass average of the other two elements

State the physical properties of sodium .

• Ans 1: 1: Its melting point is 97°C
• Ans 2: 2: Sodium is silvery white having a metallic lusture very soft and can be cut with knife

What is the relationship between empirical formula and formula unit ?

• Ans 1: All the ionic compounds are represented by formula unit . Formula unit is also and empirical formula of ionic compounds

Why do ionic compound conduct electricity in solution form . Give reason

• Ans 1: Ionic compounds are found in the form of positive and negative ions when they are in solution or molten form . When these programs are connected through a battery their ions create an opportunity for an electron (charges) to move rapidly and current begins to flow Therefore , this flow of current proved that ionic compounds are good conductors and they conduct electricity in solutions or molten form

What is difference between ion and free radical ?

• Ans 1: Free radicals :
  1: These are the atoms that have odd number of electrons . They do not have any charge
  2: They can exists in solutions as well as in air
  3: They may form in the presence of light
• Ans 2: Ion
  1:These are the atoms which bear some charge
  2: They can exists in solutions or in crystal lattice
  3: Their formation is not affected by the presence of light

Which one has more formula units : 1g of NaClor 1 g KCL ?

• Ans 1: NaCl has more formula units than KCl
  For NaCl
  Formula unit = Mass / Formula mass
  = 1/58.5
  = 0.017
• Ans 2: For KCl
  Formula units = Mass/ Formula mass
  = 1/67.5 = 0.014
• Ans 3: Result : NaCl has more formula units than KCl

Can pure gold be used for making ornaments ? If not , why ?

• Ans 1: Gold is too soft ,to be used as such . That is why it cannot be used aline in making ornaments . It is always alloyed with copper ,silver or some other metals

What is solid-solid solution ? Give two examples .

• Ans 1: Alloy: When solid solvent and solid solute make solutions it is called solid-solid solution
• Ans 2: Example : Brass, bronze

Why the density of a gas is measured in gdm^-3while that of a liquid is expressed in gcm^-3?

• Ans 1: The density of a gas is measured in gdm^-3while that of a liquid is expressed in gcm^-3because gases have large volume which is measured by large unit dm³while liquid has less volume so it is measured by small unit cm³

Why is 2nd ionization energy of magnesium very high than its 1st ionization energy

• Ans 1: Second ionization energy of magnesium is very high than its first ionization energy . Because it becomes very difficult to remove second electron from the Mg- ions as the nuclear charge attracts the remaining electrons strongly

For what purpose , Iodine-131 is used ?

• Ans 1: Isotopes of iodine I-131 is used to diagnose goiter in thyroid

Write down melting point and boiling point of sodium metal .

• Ans 1: Melting and boiling point of sodium metal are as follows
• Ans 2: Melting point :97°C
• Ans 3: Boiling point : 883°C

Give few properties of canal rays .

• Ans 1: a: Deflection of these rays in electric and magnetic field proved that these were positively charged
  
  
• Ans 2:
  b: The nature of canal rays depends upon the nature of gas , present in discharge tube
  
  
• Ans 3: c: Travel in straight line in a direction opposite to cathode rays

Differentiate between crystalline and amorphous solid .

• Ans 1: Crystalline solid : Solids in which particles are arranged in a definite three-dimensional pattern are called crystalline solid
• Ans 2: Example : diamonds , NaCl etc
• Ans 3: Amorphous solid : Solids are not regularly arranged on their regularly shapes are destroyed are called amorphous solid
• Ans 4: Example : Plastic , rubber, glass etc

Define halogens . give example .

• Ans 1:
  Halogens : The element of group 17 called halogens
  Example : Chlorine , Fluorine , Bromine etc
  
  

State the nature and name of the substance formed by combining the following

1: Zinc + Copper

2: Water +Sugar

3: Aluminum +Sulphur

4: Iron + Chromium + Nickle

• Ans 1: 1:Zinc + Copper
  It will be a mixture called a brass (alloy)
• Ans 2: 2: Water + Sugar
  It will be a solution or mixture called sugar syrup
• Ans 3: 3: Aluminum + Sulphur
  It will b a compound called aluminum sulphide
• Ans 4: 4: Iron + Chromium + Nickle
  It will be a mixture called nichrome (alloy)

Which gasses are present in air ? Write their names .

• Ans 1: Oxygen , nitrogen , carbon dioxide , argon are major gasses present in air

Difference between molecular mass and formula mass.

• Ans 1: Molecular Mass:
  The sum of the atomic mass of all the elements present in a molecule is called as Molecular Mass.
  
  
• Ans 2: Formula Mass:
  The sum of atomic masses of all the elements present in a formula unit of an ionic compound is called formula mass.

For what purpose P-32 and Sr - 90 are used .

• Ans 1: 1: For the treatment of skin cancer , isotopes like P-32 and Sr-90 are used because they emit less penetrating beta radiations
• Ans 2: 2: For cancer , Co-60 affecting within the body , is used because it emits strongly penetrating gamma rays

Define groups ?

• Ans 1: The vertical columns in periodic table are called groups . Numbered from 1 to 18

Explain how anode rays are formed from the gas taken in the discharge tube .

• Ans 1: Anode rays are produced when the cathode rays collide with residual gas molecules present in the discharge tube and ionize them as follows
  M+ le^-➜ M⁺ +2e^-

Write down use of paints and greases .

• Ans 1: 1: Greasing or painting of the surface can prevent the corrosion of iron
• Ans 2: 2: With development of technologies , modern paints contains a combination of chemicals called 'stablizers ' that provide protection against the weathering and other atmospheric effects
• Ans 3: 3: Iron can be prevented from rusting by applying layer of grease

Define biochemistry ?

• Ans 1: It is the branch of chemistry in which we study the structure , composition , and chemical reaction of substances found in living organisms (i-e humans ,animals and plants )

What do you mean by malleability?

• Ans 1: Malleability is the property by virtue of which metals can be drawn into sheets.

Define unsaturated solution .

• Ans 1: The solution which have capacity to dissolve more amount of solute is called unsaturated solution

Name a metal which exists in liquid form? Ans: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state

• Ans 1: All metals exists in solid state, only mercury (Hg) is the metal which exist in liquid state

What are the defects of Mendeleev's periodic table or why improvement was make in Mendeleev's periodic table?

• Ans 1: There are two defects in Mendeleev's periodic table:
  
  
• Ans 2: 1: His failure to explain the position of isotopes
• Ans 3: 2: Wrong order of atomic masses of some elements

Why melting point and boiling points of ionic compounds are high?

• Ans 1: Melting and boiling of ionic compounds are high because thy consists of positive and negative ions . There exists very strong electrostatic interaction between these charged ions . That is why a lot of force is required to break these forces

State the physical properties of sodium .

• Ans 1: 1: Its melting point is 97°C
• Ans 2: 2: Sodium is silvery white having a metallic lusture very soft and can be cut with knife

Differentiate between homoatomic and heteroatomic molecules with examples .

• Ans 1: Homoatomic molecules : A molecule containing same type of atoms is called homoatomic molecule
• Ans 2: Example : H₂ O₃ S₈
• Ans 3: Heteroatomic molecules : A molecule containing different kinds of atoms is called heteroatomic molecule
• Ans 4: Example : CO₂ ,H₂O ,NH₃

Explain the law of flow of heat ?

• Ans 1: In winter atmospheric temperature falls lower than that of our body temperature . According to principle of heat flow out from our body and we feel cold . To control this outward flow of heat , we wear black and warm clothes . To maintain body temperature we use dry fruits tea, coffee and meats etc

How many sub shell are there in second sub shell ?

• Ans 1: In second sub shell 'L ' has two sub shells s and p
• Ans 2: L shell =s, p sub shell

Which are long periods ? How many elements are present in long periods ?

• Ans 1: 4th and 5th periods of the long firm of table are called long periods of periodic table . Both these periods consists on 18 elemensts present in each

Why metallic character decrease along a period and increase in a group?

• Ans 1: Along the period: Metallic character decreases along the period from left to right.
  Reason:
  1:. From left to right size of atom decreases and nuclear charge increases so is difficult to remove electron and electropositivity decreases.
  
• Ans 2: 2:From left to right nuclear charge increases
  
  
• Ans 3: In a group: In group metallic character increases from top to bottom
  Reason :
  1: As going down the group size of atom increases
  2: From top to bottom nuclear charge decreases

State whether allotropy is shown by elements or compounds or both ?

• Ans 1: Allotropy is only shown by elements . It is not a property of compounds

iodine exists in solid state, can it be beaten with hammer to form sheets?

• Ans 1: No, only solid metals have the characteristic to be beaten with hammer to for sheet

What is difference between solution and mixture ?

• Ans 1: Solution : Homogenous mixture of two or more substance called solution
• Ans 2: Example : A solution of salt in water
• Ans 3: Mixture may be homogenous or heterogenous
• Ans 4: Example : Air is the mixture of many gases

Write formulas of two ionic compounds which are soluble in water .

• Ans 1: The two ionic compound which are soluble in water are following
• Ans 2: Sodium chloride : NaCl
• Ans 3: Sodium Thiosulphate : Na₂S₂O₃

Define homogenous mixture and give example .

• Ans 1: Homogenous mixture: The mixture having uniform composition is calledhomogenous mixture
• Ans 2: Example : Ice cream , gasoline , air etc
• Ans 3: Heterogenous mixture : The mixture which does not have uniform composition is called heterogenous mixture
• Ans 4: Example : Rock ,soil, wood etc

Write example of use of radioactive isotopes in the field of medicine and radiotherapy

• Ans 1: In the field of medicine isotopes of iodine I -131 are used for diagnosis of goiter in thyroid gland . While P-32 and Sr 90 are used in the field of radioactivity

Write down the position of hydrogen in the periodic table

• Ans 1: First periodic starts from hydrogen due to one electron in its valence shell it lies in the first group and first period

Define avagadro's number

• Ans 1: Avagadro's number is a collection of6.02 × 10^{23 particles. It is represented by symbol 'NA'. Hence the6.02 × 1023 number of atoms , molecules or formula unit is called avagadro's number that is equal to 1 mole of respective substance}

How will you compare he electropositivity ok alkali metals and alkaline earth metals ?

• Ans 1:
  :Alkali metal
  These are highly electropositive. They have highly ionization energy values ranging from 520k.Jmol 1 for Li to 376 k.Jmol 1 for CS
  Alkaline earth metal :They have less ionization energy values ranging from 1787k.Jmol 1 for Be to 936 k.Jmol 1 for Ba
  
  

What is the trend of ionization energy in the group ?

• Ans 1: As we move down the group , more and more shells lie between the valence shell and the nucleus of the atom , these additional shells reduce the electrostatic force felt by the electrons present in the outermost shell . Resultantly the valence shell electrons can be taken away easily . Therefore , ionization energy of elements decreases from top to bottom in a group

What is difference between group and period ?

• Ans 1: Group : The vertical columns present in periodic table are called groups .There are 18 groups present in the periodic table
• Ans 2: Period: The horizontal rows present in periodic table are called period .There are 7 periods present in the periodic table

What is valency ?

• Ans 1: The combining capacity of an element with other element is called valency
• Ans 2: For example : Valency of carbon is 4

Differntiate between biochemistry and industrial chemistry .

• Ans 1: Biochemistry : Biochemistry is the branch of chemistry in which w study the structure , composition , and chemical reaction of substances found in living organisms
• Ans 2: Industrial chemistry : Industrial chemistry is the branch of chemistry that deals with the manufacturing of chemical compounds in commercial scale is called industrial chemistry

Differentiate shell and sub-shell with example of each ?

• Ans 1: Shell (Orbit):
  The circular orbits of specific energy are called shells or energy levels

  
  
• Ans 2: Represent : They are represented by capital alphabets e.g K,L,M,N
• Ans 3: Sub-shell (Orbital) : Shells are further divided into sub-shell
  
  
• Ans 4: Represent : They are represented by small alphabets
  e.g s,p,d,f

Calculate molecular mass of NH3.

• Ans 1: Molecular mass :
  NH3 =14+1*3
  =17a.m.u

What is periodic law?

• Ans 1: In 1913, H. Moseley observed that atomic number instead of atomic mass should determine the position of elements in the periodic table and according the periodic law was amended as properties of elements are periodic function of their atomic numbers

Describe atIeast two necessary conditions for the formation of a covalent bond.

• Ans 1: Iwo necessary conditions for the formation of covalent bond are: (.) The electronegativity difference between atoms must be less. So. that the shared pair of electrons is attracted by both the atoms equally. (i1) Maximum 3 to 6 electrons are present in their valence shells

Which isotopes are called radioactive isotopes ?

• Ans 1: The isotopes have ability to emit radiation naturally called radioactive isotopes

Define atomic radius ?

• Ans 1: The half of the distance between the nuclei of the two bonded atoms referred as atomic radius

What do you mean by 1 atom of C and 1 gram of atom of C ?

• Ans 1: One atom of carbon has its atomic mass which is 12 amu . But when this mass of carbon atom atom is expressed in grams then it is known as gram atomic mass . As 1 gram of carbon = 12.0 g

Differentiate between solute and solvent ?

• Ans 1: Solute : The component which is present in smaller quantity is called solutee.g : Salt in water , salt is solute
• Ans 2: Solvent : The component of solution which is present in larger quantity is called solvente.g : salt in water , water is solvent

Define oxidizing and reducing agents with example .

• Ans 1: Oxidizing agent:
  1: Oxidizing agent is the species that oxides a substance by taking electrons from it
  2: The substance (atom or ion ) which is reduced itself by gaining electrons is also called oxidizing agent
  
  
• Ans 2: Example : Nin-metals are oxidizing agents because they accept electrons being more electronegative elements
• Ans 3: Reducing agent :
  1: Reducing agent is the specie that reduces a substance by donating electron to it
  2: The substance (atom or ion ) which is oxidized by losing electrons is also called reducing agent
• Ans 4: Example : Almost all metals are good reducing agents because they have the tendency to loose electrons

Why is 2nd ionization energy of magnesium very high than its 1st ionization energy

• Ans 1: Second ionization energy of magnesium is very high than its first ionization energy . Because it becomes very difficult to remove second electron from the Mg- ions as the nuclear charge attracts the remaining electrons strongly

How can you justify that air is a homogenous mixture . Identify substance present in it ?

• Ans 1: Air is a mixture formed by the physical mixing of the substance like nitrogen , oxygen ,carbon dioxide , noble gases and moisture and it has same composition throughout , so it is homogenous mixture

On which two factors vapour pressure of any liquid depends ?

• Ans 1: Vapour pressure of liquid depends upon following factors :
• Ans 2: Nature of liquid : Polar liquids have low vapour pressure than non polar liquids
• Ans 3: Size of molecule : Small sized molecules have high vapour pressure

Why and how are element arranged in 4th period ?

• Ans 1: Elements are arranged in 4th period according to increasing atomic number . The 4th period contains 18 elements beginning with potassium and ending with krypton . As a rule . 4th period elements fill their 4th subshells in that order however there are exception such as chromium

Why is platinum is used to make jewelry ?

• Ans 1: Platinum is used to make jewelry items because of its unique characteristics like colour , beauty , strength, flexibility and resistance to tarnish . It provides a secure setting for diamonds and other gemstone , enhancing their brilliance

Why the electrons move freely in metals ?

• Ans 1: This is because the valence shell electrons loosely held by nucleus of an atom . There is the weak force of attraction present between nucleus and the mobile valence electrons . Therefore valence electrons move freely in metals

Why noble gases are not reactive ?

• Ans 1: The noble gases have 2 or 8 electrons in their valence shells i-e the valence shell of all the noble gases is complete . Their atoms do not have vacant space to accommodate extra electrons , So noble gases are not reactive

Classify the following into elements , compound and mixture ?

1: He and H2

2: CO and Co

3: Water and milk

4: Gold and brass

5: Iron and steel

• Ans 1: Elements :
  He , H₂ ,Co, Gold , Iron
• Ans 2: Compounds :
  CO , H₂O
• Ans 3: Mixture :
  Milk , Brass , Steel

How platinum is used as a catalyst in automobiles and what are advantages of this use ?

• Ans 1: Platinum alloyed with palladium and rhodium is used as a catalyst in automobile as catalyst converter . It converts harmful gases into harmless gases

Write down the name of four least reactive metals .

• Ans 1: The names of least reactive metals are following
• Ans 2: 1: Gold
• Ans 3: 2: Silver
• Ans 4: 3:Platinim
• Ans 5: Copper

What is atomic number of phosphorous ? Write down its electronic configuration .

• Ans 1: Atomic number of phosphorous (P) is 15
  Electronic configuration
  1s² , 2s² ,2p⁶ ,3s² ,3p³

Define periods ?

• Ans 1: Seven horizontal rows present in periodic table are called periods . Numbered from 1 to 7

Which salt is used as electrolyte in chromium electroplating ?

• Ans 1: In electroplating of chromium Sulphate Cr₂(SO₄)₃ is used an electrolyte

Calculate the molecular mass of the carbon dioxide .

• Ans 1: Molecular mass of the carbon dioxide
  CO2 = 12+2 (16)
  = 44amu

Define carbondating .

• Ans 1: 1: The radioactive isotopes are used to estimate the age of fossils like dead plants and animals and stones etc . The age determination of very old objects based on the half-lives of the radioactive isotopes is called radioactive isotopes is called radioactive-isotopes dating
• Ans 2: 2: An important method of age determination of old carbon containing objects ( fossils ) by measuring the radio-carbon dating or simple carbon dating

Why are the colloids quite stable ?

• Ans 1: In colloid particles are large but not large enough and they are stabilized hence they do not settle down for a ling time that is why colloids are quite stable

Why volume of gas decreases with increase of pressure ?

• Ans 1: Volume of gas decreases with increase of pressure because of empty spaces between their molecules . When gases are compressed the molecules come closer to one another and occupy less volume as compared to the volume in uncompressed state .

Why does evaporation cause cooling ?

• Ans 1: When the high kinetic energy molecules evaporates from the surface of liquid , the temperature of the remaining molecules falls down . To compensate the energy decrease , the molecules absorb heat from surrounding falls down and we feel cooling
• Ans 2: Example : When we put a drop of alcohol on palm it evaporates and our palms feels cold

Calculate the oxidation number of nitrogen in HNO₃ .

• Ans 1: HNO_{3 = (1) +(N) +3 (-2)}
  _{= 1+N-6}
  _{N = +5}

Give the reason for the decrease of electronegatively in down the group .

• Ans 1: Electronegatively decreases down a group because size of the atom increases . The attraction for the shared pair of electrons weakens
• Ans 2: For example :electronegatively values of group 17 (halogens) decreases down the group

Why alkali metals are more reactive than alkaline earth metals ?

• Ans 1: Alkali metals are extremely reactive because of their ns¹valence shell electronic configuration . As there is only one electron in their valence shell , it can be easily given out . It is the reason that they are always found in in nature as cations with +1oxidation state . Therefore , they readily form salts with non-metals
• Ans 2: The alkaline earth metals are smaller and have more nuclear charge . They have two electrons in their valence shell i-e ns². They are also reactive but less than alkali metals

Why ionic compounds are easy soluble in water?

• Ans 1: Water is polar compound while ionic compound dissolves and forms cation and anion . Cation makes force of attraction with negative pole of water , while anion with positive pole of water and dissolve in water

Find out the mass of 3 moles of oxygen atoms .

• Ans 1: 3x16 = 48g of oxygen are present in 3 moles

Convert 560 torr into cmHg

• Ans 1: 1 torr = 1mm Hg
• Ans 2: 1mm = 1cm/10
  1 torr = 1/10cmHg
• Ans 3: 560 torr = 1/10 cmhg x 560
  = 56 cm Hg

Why is the ionization energy of Na more than 'K'?

• Ans 1: The first ionization of Na (495,8kJ/mol ) is greater than first ioniztaion energy of 'K' (418.8kJ(mol) and the atomic size of Na is less than 'K' so the energy required to remove an electron from outermost shell of Na is greater than that ok K ,so the ionization energy of Na is more than k

Write any two rules for assigning oxidation number .

• Ans 1: 1: The oxidation number (O.N) of an ion consisting on a single element is the same as the charge on that ion .
• Ans 2: 2: In any substance the more electronegative atom has the negative O.N
• Ans 3: 3: In a neutral molecule , the sum of the O.N of all the elements is zero
• Ans 4: 4: The sum of O.N in ion is equal to the charge present on ions

What is difference between valency and oxidation ?

• Ans 1: Valency : Valency is the combining capacity of an atom with other atoms . It depends upon the number of electrons in the outermost shell
• Ans 2: 2: Valency is written as the sign followed by the number i-e 2 +
  Example :
  Valency of chlorine is 1
• Ans 3: Oxidation state :
  Oxidation state or oxidation number (O.N) is the apparent charge assigned to an atom of an element in a molecule or in an ion
• Ans 4: 2: Oxidation state is written as the sign precedes the number . It is written as +2
• Ans 5: Example In HCL , oxidation number of H is +1 and that of Cl -1

Define molarity and write its equation .

• Ans 1: It is a concentration unit defined as number of moles of solute dissolved in one dm3 of solution . It is represented by M.
• Ans 2: Formula :
  Molarity = No.of moles of solute / Volume of solution (dm³)
• Ans 3: Molarity M = Mass of solute (g) /Molar mass of solute (gmol ^-1) x Volume of solution x (dm^-3)

Give chemical reaction of methane with chlorine in bright light .

• Ans 1:
  In bright light (sun light) Cl2 react with CH4 violently and explosively
  Chemical reaction : CH4 +2Cl2 ➜ C+4HCL

How many times is 1 mole of oxygen atoms calculate the mass of one atom of oxygen in grams

• Ans 1: One mole of oxygen atom is 16 times heavier than the one mole of hydrogen

Why densities of gases are less than liquids ?