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

Preparations for exams is the most stressful part in a student's life and it became tougher when a student has not any particular know-how that how to do preparations for exams and how to get good results. Students who as a beginners in their board exams are mostly very anxious from their tip to toe because they can't feel satisfied with how much they prepared for their board exams, and that's a common problem among all the students of BISE, this issue now finally has been resolved by the hardships of this website ilmkidunya because this website portal give all the BISE students in Pakistan an online preparation method from where a student is easily re-test himself/herself before starting of taking their boards exams.

Chemistry, when a student firstly listens to this subject name they definitely come in stress because the chemistry subject is as difficult as its name indicates it. When a student starts its preparation for exams he/she feel uneasy to learn some subjects chemistry is also one of them because of containing many numerical, balance chemical equations, chemical reactions, and its end products and many other things. To get a full grip and strong command on this entire subject a student is need to understand this subject high logics which is mostly based on its chemical equations, chemical reactions and also the numerical side which if a student is well practiced in solving these things he/she must get the highest grade in his/her board exams because these mathematical base questions give you full marks present in any subject.

Understanding the need for the student the ilmkidunya.com organize the online preparations setup for all the ninth class students according to the syllabus issued from the board of examination. This website provides a platform where the students can easily prepare themselves for all subjects of the ninth class before their exams by explaining each subject in a simple and easy way. This site dividing the chapters in the form of units and each unit is given in the form of the short questions and their appropriate answers, and a timer is also given there because all these setups are produced for the students to prepare themselves according to the board exams pattern. By solving each unit of every subject, a student is easily capable to solve the whole question paper in exams because this website gives a highly emphasize on every topic and provided all the basic and essential requirements according to the demand and needs of the student and the educational board in Pakistan.

This online preparation method is fully free to practice test session for all the students of ninth class and any student can use it after login itself in it. It is too simple to do and too useful for exams preparations.

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9th Class Chemistry Chapter 1 Online Preparation
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Online Short Questions For Chapter 1 "9th Class Chemistry English Medium Chapter 1 Preparation "

Try The Short Questions For 9th Class Chemistry English Medium Chapter 1 Preparation

  • Total Questions10

  • Available Sets86

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Chemistry (New Book) - 9th Class Chemistry English Medium Chapter 1 Preparation

Question # 1

How does electron differ from a neutron ?

  • Ans 1: Electron
    1: Electrons have negative charge
    2: The mass of the electron is 1940 times less than proton
  • Ans 2: Neutron:
    1: Neutron carry no charge
    2: Mass of neutron nearly equal to the mass of the proton
Submit

Prepare Complete Set Wise Questions For Chapter 1 "9th Class Chemistry English Medium Chapter 1 Preparation "

9th Class Chemistry English Medium Chapter 1 Preparation - Set 1

Question # 1

How does electron differ from a neutron ?

  • Ans 1: Electron
    1: Electrons have negative charge
    2: The mass of the electron is 1940 times less than proton
  • Ans 2: Neutron:
    1: Neutron carry no charge
    2: Mass of neutron nearly equal to the mass of the proton
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 2

Question # 1

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

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

9th Class Chemistry English Medium Chapter 1 Preparation - Set 3

Question # 1

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:
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 4

Question # 1

Write chemical formula of caustic soda and washing soda .

  • Ans 1: Caustic soda: NaOH
  • Ans 2: Washing soda: Na2CO3.10H2O
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 5

Question # 1

In which pattern modern periodic table was arranged?

  • Ans 1: According to increasing atomic number.
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 6

Question # 1

What do you mean by malleability?

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

9th Class Chemistry English Medium Chapter 1 Preparation - Set 7

Question # 1

What do you mean like dissolve like ? Explain with example ?

  • Ans 1: The general principle of solubility is , like dissolve like
    1: The ionic and polar substance are soluble in polar solvents . ionic solids and polar covalent compounds are soluble in water e.g KCl , Na2CO3, CuSO4etc
  • Ans 2: 2: Non -polar substances are not soluble in polar solvents . Non polar covalent compounds are not soluble in water but dissolve in petrol and benzene etc
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 8

Question # 1

Why the trend of electron affinity and electron -negativity same in the period?

  • Ans 1: The electron -negativity and electron affinity , both depends upon the size of atom and the nuclear charge . In the period from left to right the nuclear size decreases and nuclear charge increases . Therefore the trend of both is same
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 9

Question # 1

Write down two uses of gold .

  • Ans 1:
    Because of its inertness in atmosphere , it is an ornamental metal as well as used in making coins . Gold is too soft to be used as such
    It is always alloyed with copper, silver or some other metal
  • Ans 2:

Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 10

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 11

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 12

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 13

Question # 1

Describe the number of molecules in 9 g water.

  • Ans 1: Volume of water = 9g
  • Ans 2: No of molecules in a gram of water = 9/18
    = 0.5 mole
  • Ans 3: No of molecules in 9g gram of water molecules = 0.5x6.02x10 23
    = 3.01x1023
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 14

Question # 1

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

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

9th Class Chemistry English Medium Chapter 1 Preparation - Set 15

Question # 1

Why is the formula of solute necessary for calculation of the molarity of the solution ?

  • Ans 1: Formula of solute is necessary for calculation of the molarity of the solution because molarity depends upon No. of moles of solute
  • Ans 2: Molarity = No of moles of solute / Volume of solution (dm3)
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 16

Question # 1

Define chemical formula and give one examples .

  • Ans 1: Definition : A chemical formula is the symbolic representation the elements in the compounds and the ratio of the elements to one another
  • Ans 2: Example : Chemical formula of water is H2O
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 17

Question # 1

What are metalloids ? Give two examples .

  • Ans 1: The elements whose properties are intermediate between metals and non-metals are called metalloids
  • Ans 2: Example Boron, Silicon, and etc
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 18

Question # 1

Define periods ?

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

9th Class Chemistry English Medium Chapter 1 Preparation - Set 19

Question # 1

How does nature of attractive forces of solute-solute solvent -solvent affect the solubility?

  • Ans 1: Solutions formation depends upon the relative strength of attractive forces between solute - solute , solvent-solvent and solute-solvent . Generally solutes are solids , ionic solids are arranged in such a regular pattern that the inter ionic forces are at a maximum . If the new forces between solute and solvent particles overcome the solute-solvent attractive forces , then solute dissolves and make a solution . If the forces between solute particles are strong enough then solute-solute forces , solute remains insoluble and solution is not formed
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 20

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 21

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 22

Question # 1

Find out the mass of 3 moles of oxygen atoms .

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

9th Class Chemistry English Medium Chapter 1 Preparation - Set 23

Question # 1

What type of attractive forces exist between HCL molecules ?

  • Ans 1: Dipole-dipole attractiveforces exist between HCL molecules.
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 24

Question # 1

How many atoms of hydrogen present in one mole of water ?

  • Ans 1: One molecule of water is made up of two atoms of hydrogen and 1 atom of oxygen , hence 2×6.02×1023.atoms of hydrogen and6.02×1023 atoms of oxygen constitute one mole of water
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 25

Question # 1

What is relation between electropositivity and ionization energy ?

  • Ans 1: Electropositivity is the reverse of the ionization energy . In the from from top to bottom ionization energy decreases and electropositivity increases
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 26

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 27

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 28

Question # 1

Why O2 is necessary for rusting ?

  • Ans 1: Rusting is the oxidation of any metal . The important condition for rusting is moist air (air having water vapours formed which is called rust . In the absence of oxygen this reaction did not take place due to which rusting dis not happen
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 29

Question # 1

What is difference between solution aqueous solution ?

  • Ans 1: Solution : A solution is a homogenous mixture of two or more substance
  • Ans 2: Example : Air is the solution of many gases
  • Ans 3: Aqueous solution: The solution which is formed by dissolving a substance in water is called aqueous solution
  • Ans 4: Example : Solution of salt in water
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 30

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 31

Question # 1

Differentiate between homoatomic and heteroatomic molecules with example.

  • Ans 1: Homoatomic molecules; A molecule containing same type of atoms is called monatomic molecule.
    for example: H2, O3, S8
  • Ans 2: Heteroatomic molecules:A molecule consists of different kinds of atoms. It is called as heteroatomic molecule.
    For example: CO2, H2O, NH3
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 32

Question # 1

6: Complete the following chemical equation :
1: Ca + H2 ➜ , 2: Ca + Cl2

  • Ans 1:
    Calcium reacts with hydrogen at high temperature of form hydrides
    1: Ca +H2 ➜ CaH2
  • Ans 2:
    Calcium and chlorine reacts slowly to form halides
    2: Ca + Cl2 ➜ CaCl2
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 33

Question # 1

What is matter ?

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

9th Class Chemistry English Medium Chapter 1 Preparation - Set 34

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 35

Question # 1

Why is 02 necessary for rusting?

  • Ans 1: 02 is necessary for rusting because it acts as oxidizing agent. It first oxidize iron-to Fe+2 ion thus Fe+ ion to rust (Fe203.n H2O) in the presence of water.
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 36

Question # 1

What happens at cathode in galvanic cell ?

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

9th Class Chemistry English Medium Chapter 1 Preparation - Set 37

Question # 1

What is compressibility?

  • Ans 1: Decrease of volume by increasing pressure is called compressibility of that thing like gases . Gases are highly compressible due to empty spaces between their molecules
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 38

Question # 1

How does nature of attractive forces of solute-solute solvent -solvent affect the solubility?

  • Ans 1: Solutions formation depends upon the relative strength of attractive forces between solute - solute , solvent-solvent and solute-solvent . Generally solutes are solids , ionic solids are arranged in such a regular pattern that the inter ionic forces are at a maximum . If the new forces between solute and solvent particles overcome the solute-solvent attractive forces , then solute dissolves and make a solution . If the forces between solute particles are strong enough then solute-solute forces , solute remains insoluble and solution is not formed
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 39

Question # 1

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

  • Ans 1: Gram molecular mass
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 40

Question # 1

Briefly describe the mobility of gases.

  • Ans 1: Gas molecules are always in state of continuous motion . They can move from one place to another because gas molecules have high kinetic energy . This continuous motion of gases is called mobility of gases
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 41

Question # 1

Write down two uses of gold .

  • Ans 1:
    Because of its inertness in atmosphere , it is an ornamental metal as well as used in making coins . Gold is too soft to be used as such
    It is always alloyed with copper, silver or some other metal
  • Ans 2:

Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 42

Question # 1

What do you mean by malleable and ductile ?

  • Ans 1: Malleability is the property by virtue of which metals can be drawn into sheets while ductility is the properties by virtue of which a metal can be drawn into wires
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 43

Question # 1

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 .
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 44

Question # 1

Give two examples of gas in liquid solution .

  • Ans 1: 1: Fog
  • Ans 2: 2: Mist
  • Ans 3: 3: Liquid in pollutions
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 45

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 46

Question # 1

What is effective nuclear charge ?

  • Ans 1: The valence electron of an atom experiences less nuclear change than that of actual charge , it is called effective nuclear charge or Zeff
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 47

Question # 1

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 .
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 48

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 49

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 50

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 51

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 52

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 53

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 54

Question # 1

Explain Dobereiner's triads .

  • Ans 1: Dobereiner observed relationship between atomic masses of several groups of three elements called triads . In these groups , the central or middle element had atomic mass average of the other two elements
  • Ans 2: Example : One triad group is consists of calcium strontium (88) and barium (137) . In this group atomic mass of strontium is the average of the atomic masses of calcium and barium
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 55

Question # 1

Difference between substance and mixture.

  • Ans 1: Substance: A piece of matter in pure form is termed as substance.
    e.g. Glucose (C6H12O6) Oxygen
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 56

Question # 1

What type of elements form metallic bond?

  • Ans 1: Metals form metallic bond
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 57

Question # 1

Differentiate between substance and mixture .

  • Ans 1: Substance : A piece of matter in pure form is termed as substance
    e,g Glucose (C6H12O6 ) Oxygen
  • Ans 2: Mixture : Impure matter is called mixture
    e.g Soil , Milk etc
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 58

Question # 1

Define transition temperature . Give example .

  • Ans 1: The temperature at which one allotropes changes into another is called is called transition temperature
  • Ans 2: Example: Transition temperature of sulphur is 96°CSulphur exists in rhombic form under 96°C it changes in monoclinic form . After this temperature i-e 100°C sulphur exists in monoclinic form
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 59

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 60

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 61

Question # 1

In electroplating of silver , from which electrolyte Ag+ come or where they deposit ?

  • Ans 1: In the electrolyte of silver (Ag+) comes from anode and deposit on cathode
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 62

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 63

Question # 1

Calculate the gram molecule in 40g of phosphoric acid

  • Ans 1: Molar mass of phosphoric acid H3PO4 = 3+31+64=98
  • Ans 2: Number of moles = 40/98
    = 0.408
  • Ans 3: Number of molecules = 6.02 x 10 23 x 0.408
  • Ans 4: Number of molecules = 2.45616 x 1023
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 64

Question # 1

Describe the non-metallic character in groups and period of a periodic table

  • Ans 1:
    Non-metallic charactyer in groups : In groups electrnegativity decreases from up to top bottom therefore non-metallic characrter alse decreases from top to bottom
    Non-metallic charactyer in periods : In periods , electron affinity from left to right , due to which metallic character also increases
    Due to this reason , fliorine is most non-metallic element in nature
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 65

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 66

Question # 1

What is the sign of stability of an atom ?

  • Ans 1: The sign of stability of an atom IS achieving the electronic configuration similar to noble gases (He , Ne , or Ar etc) i-e (n2 p6 ) or having two or eight electrons in their valence shell . In other words an atom is called stable if it follows duplet or octet rule
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 67

Question # 1

How electroplating of zinc is carried out ?

  • Ans 1: The target metal is cleaned in alkaline detergent type solutions , and it is treated with acid , in order to remove any rust or surface scales. Next the zinc is deposited on the metal by immersing it in a chemical bath containing electrolyte zinc sulphate . A current is applied , which results in zinc being deposited on the target metal i-e cathode
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 68

Question # 1

Define isotope ?

  • Ans 1: Isotopes are defined as the atoms of elements that have same atomic number but different mass number
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 69

Question # 1

What id meant by atom and ion?

  • Ans 1: Atom
    1- It is the smallest particle of an smallest particle of an element.
    2- It is electricallyneutral
    3- It can take part in a chemical reaction
  • Ans 2: Ion
    1- It is the smallest unit of an ionic compound.
    2- It has a net charge on it.
    3- It is surrounded by oppositely charged ions.
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 70

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 71

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 72

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 73

Question # 1

An element in oxidation state +7 gains electrons to be reduced to oxidation state +2 . How

  • Ans 1: Suppose an element X +7

  • Ans 2: When an element X+7 gains 5 electrons its oxidation state will be +2
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 74

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 75

Question # 1

Differentiate between polar and non polar covalent bond .

  • Ans 1: Polar covalent bond : Covalent bond is formed between different atoms having different electronegativity between bonded atoms . Due to which one atom get negative and other get positive charge
  • Ans 2: Example H3- Cl3
  • Ans 3: Non Polar covalent bond : Covalent bond is formed between similar atoms having same electronegativity between bonded atoms . is called non polar covalent bond
  • Ans 4: Example H-H
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 76

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 77

Question # 1

Write down the names of elements of groups 1 with their symbols .

  • Ans 1: 1st group elements are called alkali metals . It consists of hydrogen (H) , lithium (Li) , sodium (Na) , potassium (K) , rubidium (Rb) and cesium (Cs) , and francium (Fr)
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 78

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 79

Question # 1

Why metals are good conductor of electricity ?

  • Ans 1: Metals are good conductors of heat and electricity in solid and liquid state due to mobile electrons
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 80

Question # 1

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
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 81

Question # 1

Why cesium (At.No.55 ) requires little energy to release its one electron present in their outermost shell ?

  • Ans 1: Cesium is the 2nd last element of 1st group . It has large size and less force of attraction between the nucleus and valence electron , as a result small amount of energy is required to remove electron from the valence shell
Submit

9th Class Chemistry English Medium Chapter 1 Preparation - Set 82

Question # 1

Write down the reaction of magnesium with oxygen . How oxygen reacts with magnesium ?

  • Ans 1: Magnesium reacts with oxygen and magnesium oxide is formed
  • Ans 2: 2Mg +O2➜ MgO
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 83

Question # 1

What are Lanthanide and actinide series ?

  • Ans 1: Due to space problem two series of elements are placed below periodic table
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 84

Question # 1

Does Kelvin scale show negative temperature?

  • Ans 1: No. Kelvin scale does not show a negative temperature
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 85

Question # 1

Define electronic configuration ?

  • Ans 1: Electronic configuration : The distribution of electrons around the nucleus in various shells and sub-shells according to increasing energy , is called electronic configuration
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 86

Question # 1

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
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9th class Chemistry Chapter 1 Preparation

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