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

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

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

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

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 2

Question # 1

Calculate molecular mass of sulphuric acid .

  • Ans 1: Molecular mass of sulphuric acid H2SO4
    =2(1)+(32)+4(16)
    =98amu
Submit

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

Question # 1

Can colloids he separated by filtration, if not why?

  • Ans 1: Colloids cannot be separated by filtration because particles are big but they can pass through a filter paper.
Submit

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

Question # 1

Give the trend of ionization energy in a period ?

  • Ans 1: If we move from left to right in a period the value of ionization energy increases . Because the size of atom reduce and valence electrons are held strongly by the electrostatic force of nucleus . Therefore elements on left side of the periodic table have low ionization energies as compared to those on right side of the periodic table
Submit

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

Question # 1

What is meant by periodic function ?

  • Ans 1: Repetition of properties due to increases of atomic number after regular intervals in the periodic table is called periodic function
Submit

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

Question # 1

Write two method for prevention of corrosion .

  • Ans 1: Method for prevention of corrosion:
    Following are some method from avoiding corrosion
  • Ans 2: 1: Paints and grease:
    Greasing or painting of the surface can prevent the rusting of iron
  • Ans 3: 2: Alloying :
    Allowing of iron with other metals has proved to be very successful techniques against rusting and corrosion . The best example of this technique is stainless steel
  • Ans 4: Removal of stains : The regions in an iron rod act as the site for corrosion . If the surface of iron is properly cleaned and stains are removed , it would prevent rusting
Submit

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

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 8

Question # 1

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
Submit

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

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 10

Question # 1

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
Submit

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

Question # 1

Define symbol and valency with example .

  • Ans 1: Symbol : The representation of any element with one or two english letters is called symbol.
  • Ans 2: Example : Sodium , Calcium
  • Ans 3: Valency : Combining capacity of an element with other elements called valency , Valency depends upon number of electrons in valence shell
  • Ans 4: Example : Sodium (Na+1) Chlorine (Cl-1)
Submit

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

Question # 1

Define industrial chemistry and analytical chemistry ?

  • Ans 1: Industrial chemistry : It is the branch of chemistry that deals with the manufacturing of chemical compounds on commercial scale
  • Ans 2: Analytical chemistry : Analytical chemistry is the branch of chemistry deals with the separation and analysis of the sample to identity its components
Submit

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

Question # 1

Why volume of a gas decreases with increase of pressure"

  • Ans 1: The volume of a given mass of a gas is inversely proportional to the pressure if the temperature is kept constant' therefore while decreasing the volume of gas pressure will increase
Submit

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

Question # 1

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)
Submit

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

Question # 1

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
Submit

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

Question # 1

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
Submit

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

Question # 1

Write electronic configuration of Mg

  • Ans 1: Atomic number of Mg 12
  • Ans 2: 12Mg= 1s2 . 2s2 . 2p6 . 3s2
Submit

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

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 19

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 20

Question # 1

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.
Submit

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

Question # 1

How sodium metal is obtained from fused sodium chloride .

  • Ans 1: On the industrial scale molten sodium metal is obtained by the electrolysis of fused NaCl in the Down's cell . This electrolytic cell is a circular furnace . In the center of the furnace there is a large block of graphite , which acts as an anode while cathode around it is made of iron
Submit

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

Question # 1

How many electrons will be in M shell of an atom having atomic no 15?

  • Ans 1: Atomic number 15
    K shall = 2 electrons
    L shall = 8 electrons
    M shall = 5 electrons
Submit

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

Question # 1

How electropositivity depends upon the nuclear charge of an atom ?

  • Ans 1: Left to right in a period nuclear charge increase but the number of metals remains same thats whyleft to right there is continuous decrease in the size of atoms . Small size atoms have higher nuclear charge and thus have lower electropositivity . Large size atoms have lower nuclear charge so they have high electropositivity , so ability to liise electron is greater large sized atoms. In high nuclear charge it is difficult to lose electron . The electropositivity of elements depends upon the nuclear charge it is difficult to lose electron . The electropositivity of elements depends upon the nuclear charge
Submit

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

Question # 1

How a covalent bond becomes polar?

  • Ans 1:
    When a covalent bond is formed between two different atoms having different electronagetivity then the bond pair of electron will not be attracted equally by the bonded atoms as a result partial positive and negative charges appear on atoms and covalent bond becomes polar.

Submit

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

Question # 1

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
Submit

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

Question # 1

Why size of an atom decreases from left to right in the periodic table?

  • Ans 1: When we move from left to right in a periodic atomic number increase yet the size of atoms decrease gradually . It is because with the increase of atomic number and nuclear charge
Submit

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

Question # 1

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
Submit

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

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 29

Question # 1

Define atomic number and atomic mass .

  • Ans 1: Atomic mass :
    1: The sum of number of protons and neutrons present in the nucleus of an atom is called atomic mass
    2: It is represented by A
    Example : Atomic mass of carbon is 12
  • Ans 2: Atomic number :
    1:The number of protons present in the nucleus of an atom is called atomic number
    2: It is represented by Z
    Example : Atomic number of carbon is 6
Submit

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

Question # 1

Write name of any two elements found in gaseous state

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

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

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 32

Question # 1

Define aqueous solution

  • Ans 1: The solution which is formed by dissolving a substance in water is called an aqueous solution
  • Ans 2: Example : NaCl in water and ink in water etc
Submit

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

Question # 1

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
Submit

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

Question # 1

Why do atoms form chemical bonds?

  • Ans 1: Atoms achieve stability by attaining electronic configuration of inert gases ns2 or ns2,np6 Atoms combine with one another. which is called chemical bond.
Submit

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

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 36

Question # 1

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
Submit

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

Question # 1

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

  • Ans 1: Colloidal solution show tyndall effect and other solutions do not show tyndall effect
Submit

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

Question # 1

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
Submit

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

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 40

Question # 1

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
Submit

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

Question # 1

Which branch of chemistry deals with preparation of paints and papers ?

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

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

Question # 1

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
Submit

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

Question # 1

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
Submit

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

Question # 1

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
Submit

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

Question # 1

Why copper is used for making electrical wires ?

  • Ans 1: Copper is used for making electrical wires because it is highly ductile and least reactive . Copper is among noble metals
Submit

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

Question # 1

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
Submit

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

Question # 1

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."
Submit

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

Question # 1

What do you mean by evaporation and how it is affected by surface area?

  • Ans 1: Evaporation: The process changing of a liquid into a gas phase is called evaporation.
    Surface Area:
    Evaporation is a surface phenomenon. Greater is surface area. greater is evaporation and vice versa. For example, sometimes a saucer is used if tea is to cooled quickly. This is because evaporation from larger surface area if saucer is more than that from the small surface area of a as cup.
Submit

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

Question # 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
Submit

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

Question # 1

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.
Submit

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

Question # 1

Why ionization energy decreases in a group from top to bottom ?

  • Ans 1: When we move down the group in periodic table , more and more shells lie between the valence shell and nucleus of the atom , these additional shells reduce the electrostatic force felt by 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 the groups
Submit

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

Question # 1

Define oxidation in terms of oxygen with an example .

  • Ans 1: Oxidation : The addition of oxygen in any chemical reaction is called oxidation reaction
  • Ans 2: Example : 2ZnO +C➜ 2Zn + CO2
  • Ans 3: In above reaction carbon dioxide is produced as a result of the oxidation of carbon
Submit

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

Question # 1

Give the composition of milk .

  • Ans 1: Milk is a mixture of calcium , water ,sugar , fat , proteins , minerals, salts , and vitamins
Submit

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

Question # 1

Why ionization energy of Na is less than Mg ?

  • Ans 1: Ionization energy of Na is less than Mg because Mg has greater nuclear charge than Na and also have smaller size
  • Ans 2: Na➜ Na++ e△11 = 495Jmol-1
    Mg➜ Mg+ +e△11 = 738Jmol-1
Submit

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

Question # 1

What is the significance of chemical formula ?

  • Ans 1: 1: It represents the name of the substance e.g H2O (water)
  • Ans 2: 2: It also represents one mole of the molecules in the balance chemical equation
  • Ans 3: 3: It tells the name of the elements as present in the compound
  • Ans 4: 4: It indicates the mass of the compound in amu or grams
  • Ans 5: It is in fact one molecule or formula unit of the compound
Submit

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

Question # 1

What was the pressure inside the discharge tube in discovery of electron?

  • Ans 1: The pressure inside the tube was kept 10-4 atm
Submit

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

Question # 1

Define standard atmospheric pressure . What are its units ? How it is relate to the pascal ?

  • Ans 1: It is defined as the pressure exerted by a mercury column of 760 mm height at sea level
  • Ans 2: 1atm = 760mmof Hg =760torr
    =101325 Nm-2 = 101325Pa
Submit

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

Question # 1

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
Submit

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

Question # 1

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
Submit

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

Question # 1

Why does a dipole develop in a molecule ?

  • Ans 1: The unequal sharing of electrons between two different types of atoms make one end of molecule slightly positive and other end slightly negatively charged . As shared pair of electron is drawn towards more electronegative atom , it is partially negatively charged . The other end automatically becomes partially positively charged
Submit

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

Question # 1

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)
Submit

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

Question # 1

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
Submit

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

Question # 1

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.
Submit

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

Question # 1

Write down electronic configuration of sodium .

  • Ans 1: Electronic configuration of sodium
    11Na = 1s2 , 2s2 , 2p6 , 3s1
Submit

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

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 66

Question # 1

Define molar solution and give example .

  • Ans 1: When one mole of solute is solved on one dm3 of solvent in measuring flask then it is called one molar solution
  • Ans 2: Example : To make molar solution of NaOH , 40 grams is solved in enough water . When volume of a solution becomes one dm3 then it becomes one molar solution of NaOH .
Submit

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

Question # 1

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
Submit

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

Question # 1

Which solution is used as an electrolyte in Nelson's cell ?

  • Ans 1: In Nelson cell concentrated solution of sodium chloride is used . It is called brine solution
Submit

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

Question # 1

Why volume of a gas decreases with increase of pressure"

  • Ans 1: The volume of a given mass of a gas is inversely proportional to the pressure if the temperature is kept constant' therefore while decreasing the volume of gas pressure will increase
Submit

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

Question # 1

Give one example each of the use of radioactive isotope in medicine and radiotherapy ?

  • Ans 1: Radioactive isotopes is used in medicine
    Iodine 131
    Radioactive isotopes used in radiotherapy
    P-32
    Sr-90
    Co-60
Submit

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

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 72

Question # 1

Calculate molecular mass of sulphuric acid .

  • Ans 1: Molecular mass of sulphuric acid H2SO4
    =2(1)+(32)+4(16)
    =98amu
Submit

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

Question # 1

Give electronic configuration of hydrogen ?

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

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

Question # 1

Why does an electron fill 2p orbital and then 3s and then 3s orbital ?

  • Ans 1: As we know that electrons that electrons fill the shells as order of their increasing energy , i-e lower energy level is occupied first then the high energy level and so on . 2p orbital has lower energy than 3s orbital that is why 2p orbital is first filled and then 3s orbital
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 75

Question # 1

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

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

Question # 1

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

Question # 1

What is redox reaction ?

  • Ans 1: The reaction in which simultaneously oxidation and reduction takes place is called redox reaction
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 79

Question # 1

What is an electron affinity ? Give an example .

  • Ans 1: Trend in a group : In a group electron affinity values decreases from top to bottom because the size of an atom increases down the group . With the increase in size of atom shielding effect increase that results in poor attraction for the incoming electron i-e less energy is released out
  • Ans 2: For example : as the size of iodine atom is bigger than chlorine , its electron affinity is less than chlorine
  • Ans 3: Trend in a period : Electron affinity values increases from left to right in the period . Because the size of atoms decreases as a result the attraction of the nucleus for incoming electron increases and increase the electron affinity
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 80

Question # 1

How mass number of same elements are different ?

  • Ans 1: Isotopes of an element have same number of protons and electrons but different number of neutrons . That's why isotopes of an element have different atomic masses . Although atomic number remains same
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 81

Question # 1

What ammendment was made by H.Moseley in mendeleev periodic table ?

  • Ans 1: According to mendleeve's periodic table properties of the element are periodic function of their atomic mass . Whereas according to H . Moseley's ammendments of periodic law properties of the elements are periodic function of their atomic numbers . This shows an atomic number of an element is equal to the number of electrons in a neutral atom . So atomic number provides the basis of electronic configuration as well .
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 82

Question # 1

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'
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 83

Question # 1

What was the pressure inside the discharge tube in discovery of electron?

  • Ans 1: The pressure inside the tube was kept 10-4 atm
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 84

Question # 1

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
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 85

Question # 1

Write two / four characteristics of cathode rays.

  • Ans 1: 1: Cathode rays travel perpendicular to the cathode surface
  • Ans 2: 2: They can cast a sharp shadow of an opaque object if placed in their path
  • Ans 3: 3: These are deflected towards positive plate in an electric field showing that they are negatively charged
  • Ans 4: 4: They raise temperature of the body on which they fall
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9th Class Chemistry English Medium Chapter 1 Preparation - Set 86

Question # 1

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

  • Ans 1: Gram molecular mass
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9th class Chemistry Chapter 1 Preparation

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