CBSE Class 9 Chemistry Revision Worksheet

Q1. With the help of an activity, show that diffusion becomes faster with increase in temperature.

Q2. When magnesium burns in air, an ‘ash’ like powder is formed.

a) Name this ‘ash’ powder.

b) Is it a chemical or physical change? Why?

Q3. a) What happens when zinc granules react with dilute sulphuric acid?

c) What kind of change is observed?

Q4. Name the state which has:

a) Maximum movement of particles

b) Maximum interparticle interaction

c) Property to get compress easily

d) Fixed shape and volume.

Q5. With the help of an activity, show that gases are more easily compressible than liquids and solids.

Q6. What is latent heat? What are its types? Describe by giving one example of each type.

Q7. Give reasons for the following:

a) A rubber band is a solid, yet it changes shape.

b) Sugar crystals are solid.

c) Gases diffuse much faster in liquids than solids.

d) Solids have higher melting and boiling points as compared to liquid and gaseous states.

Q8. Name the process by which a drop of KMnO₄ spreads in a beaker of water.

Q9. When 50g of water is dissolved in 100 ml of water, there is no increase in volume. What characteristic matter is illustrated by this observation?

Q10.What happens when a beam of light is passed through a colloidal solution? Name this phenomenon.

Q11. Distinguish between:
a) Element and compound.
b) Compound and mixture.
c) Element and mixture.

Q12. Explain why air is considered a mixture and not a compound?

Q13. Give one example of each of the following:
a) A solution of gas in liquid.
b) A solution of two gases.
c) A solution of two solids.

Q14. Give reasons for the following:
a) Evaporation causes cooling.
b) Rate of evaporation of an aqueous solution decreases with increase in humidity.

Q15. You are given a mixture of sand and ammonium chloride. How will you separate the two components of the given mixture? Explain with the help of a diagram.
                                                                       OR
Write an experiment to demonstrate the sublimation of camphor or ammonium chloride. Draw a labeled diagram.

Q16. How will you separate a mixture of dyes in blue-black ink? Explain with the help of a diagram.

Q17. How are sol, solution and suspension different from each other?

Q18. After winter, Astha packed off her woolen clothes with naphthalene balls. With passage of time, these naphthalene balls becomes smaller in size. Explain Why?

Q19.What happens when a mixture containing iron filings and sulphur powder is treated with a solvent carbon disulphide:
a) Sulphur dissolves in CS₂ b) Iron dissolves in CS₂
b) Both sulphur and iron dissolve in CS₂ d) There is no change.

Q20. A solution contains 30g of sugar dissolved in 370g of water. Calculate the concentration of this solution.

Q1 What do L.P.G and B.E.C stand for.

Q2 Name a technique to separate sand from ammonium chloride.

Q3 Why sodium is light and iron is heavy?

Q4 What is plasma?

Q5 A substance has a definite volume but no definite shape .state whether the substance is solid liquid or gas.

Q6 Why is oxygen agas?

Q7 The heating curve of a pure substance at one atmospheric pressure is shown in the fig

a) what is the physical state of the substance at points 1,2,3,4,5

b) What is the melting point of the substance?

c) What is the boiling point of the substance?

d) What happens to the temperature when the substance is changing the the state?

Q8 What is the difference between gas and vapour?

Q9 Define boiling point .Give two factors on which it depends. Why is it food cooked easily in pressure cookers?

Q10 Osmosis is a special type of diffusion explain .

Q11 Compare the following in the three states of matter based on

a) Interparticle spaces b)Interparticle force of attraction c) Particle motion

Q12 It is a hot summer day ,Priya and Tom are wearing cotton and nylon clothes respectively. What do you think would comfortable and why?

Q13 The boiling point of water in Simila is lower than that of Delhi why?

Q 14convert the following into Celcius scale 470 K 300K 298K

Q 15 What are characteristics of particles of matter ?

Q.1 Identify the quantities applicable for the following symbols--- m³, K, Pa ( Pascal ), kg/m³

Q.2 Convert the following temperatures to Celsius scale--- 283K, 50K

Q.3 Write the most important value point for the following---

Give reason—Steam produces more severe burns in comparison to boiling water.

Q.4 Write the most important value point for the following---

Give reason---A desert cooler cools better on a dry summer day.

Q.5 What are the two necessary components of a solution?

Q.6 Distinguish between a homogenous & heterogenous mixture on the basis of their composition.

Q.7 A mixture ‘X’ can be separated into its constituents easily with the help of ordinary filtration. Its components are distinctly visible with the help of naked eyes. Identify mixture ‘X’.

Q.8 Write one example of each of the following---

‘Solid in solid’ solution, gas in gas solution, gas in liquid solution & solid in alcohol solution ( non-aqueous solution )

Q.9 What causes ‘Tyndall effect’ ?

Q.10 The Chemistry teacher divided Batch H1 into group ‘A’ & ‘B’. Grp ‘A’ was instructed to determine the melting point of ice where as Grp ‘B’ was asked to determine the boiling point of water. After the completion of experiment they were advised to guide the other team mates & exchange their readings.
a) State the melting point of ice & boiling point of water on a Kelvin Scale.
b) In your opinion, what value was the teacher trying to inculcate through her instructions.

Q1. What is law of conservation of Mass?

Q2. What is law of constant proportion? Explain with example.

Q3. What is an atom? Give its importance.

Q4. What do you mean by atomicity of an atom?

Q5. Define atomic mass and molecular mass.

Q6. State the postulates of Dalton’s atomic theory.

Q7. What is Avogadro’s number? How many moles of calcium carbonate are present in 10g of this substance?

Q8. Calculate the number of molecules in

i. 84.0 g of NaOH

ii. 3.32 g of H2

Q9. Calculate number of molecules of sodium atoms in

i. 92 a.m.u of Na

ii. 92 mole of Na

Q10. Write down the formulae of

i. Aluminium Chloride

ii. Magnesium Hydroxide

iii. Aluminium Sulphate

iv. Potassium Carbonate

Q11. What are the properties of canal rays?

Q12. Define atomic number and atomic mass of an element. Atomic number of an element X is 12 and atomic mass is 24. Represent its one atom

Q13. What was Rutherford’s alpha particles scattering experiment. What were the conclusions drawn from it. What were the drawbacks of Rutherford’s model of atomic structure?

Q14. Name the three sub atomic particles of an atom. What are the charges on them?

Q15. What are isotopes? What are their applications?

Q16. The average atomic mass of a sample of an element X is 16.2u. What are the percentages of isotopes ¹⁶₈X and ¹⁸₈X in the sample.

Q17. Describe Bohr’s model of an atom with the help of a diagram of a three shelled atom.

Q18. What is the electronic configuration of an atom of an element with atomic number 19.

Q19. What are the components of Biosphere?

Q20. How are clouds formed?

Q21. List any three human activities that lead to air pollution.

Q22. Why do organism need water?

Q23. What is humus? How does humus decide the structure of soil?

Q24. What is soil? How is soil formed?

Q25. What is soil erosion? What causes soil erosion?

1. Define the following terms:

(i) Boiling point

(ii) Compressibility

(iii) Rigidity

(iv) Density

(v) Latent heat of fusion

(vi) (vi) Sublimation

(vii) Latent Heat of evaporation (viii) Density

2. Give reasons for the following

(i) Smell of hot sizzling food reaches us several meters away but to get the smell from cold food we have to go close.

(ii) Cooling effect of ice at 0®c is more than same amount of water at 0°c

(iii) Clothes get dry faster in summer than rainy season

(iv) Trees bear more leaves in summer

(v) A gas fills completely the vessel in which it is kept

(vi) A diver is able to cut water in a swimming pool

3. Convert the following to celcius scale.

a) (i) 300 K (ii) 573 k

b) Convert to Kelvin scale - (i) 576°c (ii) 393°c

4. Answer the following questions

(i) What type of clothes should we wear in summer? Why?

(ii) What do you mean by concentration of a solution? Give expression for its calculation.

5. Explain the meaning of

(i) 10% NaOH solution by mass

(ii) 10% NaOH solution by volume

6. What is Tyndall effect? Give two examples.

7. 18g of sodium chloride is dissolved in 82 g of water. Calculate the concentration of solution in Terms of Mass by mass percentage.

8. How can you separate Kerosene oil from water? Describe an activity to explain?

9. What is centrifugation? Write its two applications.

10. Explain the following with example.
(i) Chromatography
(ii) Crystallisation

11. Differentiate between
(i) Mixture and compounds
(ii) Physical change and chemical change
(iii) Homogeneous Mixture and Heterogeneous Mixture
(iv) Metals and non-metals

12. Classify the following as chemical or physical change
(i) Melting of butter
(ii) Burning of paper
(iii) Boiling of water to steam
(iv) Cutting of trees
(v) Making of fruit salad

One mark each:

1. Define atomic mass unit?

2. Define Mole?

3. An atom has electronic configuration of 2, 8, 7
(1) What is the atomic number of the element?
(2) Which of the following elements have same number of valence electrons N(7) , F(9) , P(15) , Ar(18)

4. Why are He, Ne and Ar are Inert?

5. Why are all electrons called fundamental particles of all atoms?

6. Calculate the value of moles in 17g of H₂O₂.[(H =1u) , O =16u]

7. What is meant by Avogadro ‘s constant?

8. State Law of conservation of mass.

9. Calculate the number of molecules in 4g of methane (C=12u, H =1u)

10. What are isotopes? Give examples.

2 marks each:

11.What is the electronic configuration of Na+,if atomic No, of Na atom is 11.What is the atomic No. and atomic mass of Na^{+ .}

12.Which of the two would be chemically more reactive element ‘X’ of atomic No.18 or element ‘Z’ of atomic No. 16 and why?

13.What is the difference between sodium atom and sodium ion?

14.How many molecules are present in
(a) 9g of water (b) 17g of NH₃ .
(H = 1u, O = 16u, N =14u)

15.Calcium and Oxygen are combined in the rates of 5:4 by mass to form calcium oxide. What mass of oxygen gas would be required to react with 2.5g of calcium?

16.How many atoms of carbon and hydrogen are present in 3 moles of ethane
(C₂ H₆) .

17.The atomic number of Aluminum is 13 and that of Chlorine is 17.How many electrons , protons and neutrons are present in Al₃ and Cl^- ions.

18.What you meant by valence electrons?
(1) Write the electronic configuration of elements potassium (19) and N (7)
(2) Write the No.of valance electrons in each of these elements?

19.An element has three valence electrons in the 3^rd shell. Name the element and give its atomic No. and state is it a metal or non-metal?

20.Calculate the mass of 6.022 x 10 ²³ N₂ molecules. (N = 14u)

3 mark each:

21. Write the chemical formula for the following:
(1) Ammonium Carbonate.
(2) Barium Sulphate.
(3) Sodium Sulphide.
(4) Aluminium Hydroxide.
(5) Calcium Flouride.
(6) Potassium Nitrate.

22. Calculate the molecular mass of the following:
(i) (NH₄) 2SO₄ (ii) Al₂(SO₄)₃ (iii) Ca(HCO₃)₂
[ N = 14u, H =1u, S = 32u, Al = 27u, O = 16u, C = 12u ]

23.Calculate the No.of Al³⁺ ions present in 0.056g of Al₂O₃.

24.What is chemical formula? Give two information conveyed by chemical formula of a compound.

25.Explain Rutherford’s Alpha Scattering experiment for the discovery of Nucleus. Write his observations and conclusions.

26.The average atomic mass of a sample of an element X is 16.2u.What are the percentages of isotopes ¹⁶X₈ and ¹⁸X₈ in the sample.

27.(1) An ion M³⁺ has 10 electrons and 14 neutrons. What is the atomic number and mass number of M.
(2) Write the electronic configuration of the following ions.
(1) Mg²⁺ (2) O^2- (3) S^2- (4) Na⁺ (5) N^3-

28. (1) Which has more No.of atoms, 100g of Sodium or 100g of Iron
(Na =23u, Fe = 56u) .
(2) Which has more No.of molecules, 4g of CH4 and 8g of H₂O
[H = 1u, O = 16u, C = 12u ]

29. (1) For the symbol, H,Dand T Calculate three subatomic particles found in each of them?

30. If Chlorine atom is available in the form of say two isotopes ₁₇Cl³⁵ (75%) and ₁₇CL³⁷(25%) , Calculate the average atomic mass of chlorine atom.

5 Mark Questions:

31. (1) Explain Bohr model of an atom?
(2) Draw the Bohr model of the following atom
(1) Sodium (₁₁Na²³)
(2) Oxygen (₈O¹⁶)
(3) Calcium (₂₀Ca⁴⁰)

32.(1) Calculate the molecular mass of the following :
(1) CH₃-OH (2) CuSO₄.5H₂O (3) Ca(HCO₃)₂
(2) Calculate the No.of particles in each of the following:
(1) 46g of Na atoms (Na = 23u)
(2) 8g of O2 molecules
(3) 0.1 mole of carbon atoms
(4) 100g of CH₄

33. (1) What are the postulates of Dalton’s Atomic theory of matter?
(2) Define the following terms:
(i) Atomicity (ii) Valency (iii) Relative atomic mass (iv) Molecular mass

1. When we make tea/coffee/ lemonade particles of one type of matter diffuse into particles of other. Why?

2. Solution of CuSO₄ remains coloured even after large number of dilutions. Why?

3. What is the effect of temperature on kinetic energy?

4. Why can’t we cut a stream of water with fingers easily?

5. What are the fourth and fifth states of matter?

6. K.E of molecules is directly proportional to
a) temperature
b) pressure
c) both a and b
d) atmospheric pressure.

7. Which of the sets of phenomena would increase on raising the temp.
a) diffusion,evaporation,compression of gases
b) evaporation, compression of gases, solubility
c) evaporation,diffusion, expansion of gases
d) evaporation, solubility,diffusion , compression of gases.

8. Why does the level of water not change when salt is dissolved in water?

9. Define latent heat of vapourisation and latent heat of fusion.

10. Name a gas which can be solidified.

Q1 What do mean by atmospheric pressure? What are the units of atmospheric pressure?

Q2 What is Graham’s Law of diffusion?

Q3 Apart from solid, liquid and gas, what are the other two states of matter?

Q4 A punctured tyre becomes flat more easily in summer than in winter. Explain.

Q5 Which of the following is not a matter?

a) Fog

b) Humidity

c) Melting point

d) Blood

Q6 How will you demonstrate that temperature remains constant during the conversion of solid into liquid?

Q7 What do you mean by Latent heat of vaporization?

Q8 Why is ice rubbed on a burnt part of the skin?

Q9 What are metalloids?

Q10 Calculate the mass of glucose and mass of water required to make 250g of 25% solution of glucose.

Q11 Salt can be recovered from its solution by evaporation. Suggest some other techniques for the same.

Q12 Name the process associated with the following:-

a) A acetone bottle is left open and the bottle becomes empty.

b) Milk is churned to separate cream from it.

c) Fine beam of light entering through a small hole in the dark room illuminates the particles in its path.