CBSE Class 10 Chemistry Chapter 1 Important Questions:

In this Web Page, we are going to discuss the Important questions of CBSE Class 10 (Science) Chemistry Chapter 1 Chemical Reactions and Equations. It is the first chapter in Unit I Chemical Substances – Nature and Behaviour.

Unit I: Chemical Substances – Nature and Behaviour

Chapter 1 Chemical Reactions and Equations

MULTIPLE CHOICE QUESTIONS

1. When Ag is exposed to air it gets a black coating of

(a) AgNO3

(b) Ag2S

(c) Ag2O

(d) Ag2CO3

Ans:(b) Ag2S 

2. Which of the reactions is used in black and white photography?

(a) Combination Reaction

(b) Decomposition Reaction

(c) Displacement reaction

(d) Oxidation reaction

MnO2 + 4HCl →MnCl2 + 2H2O + Cl2

Ans:(b) Decomposition Reaction

3. Identify the substance oxidized in the above equation.

(a) MnCl2

(b) HCl

(c) H2O

(d) MnO2

Ans:(b) HCl 

4. Zinc reacts with silver nitrate to form which compounds?

(a) Zn (NO3)2 + Ag (b) ZnNO3 + Ag (c) AgNO3 + Zn (NO3)2 (d) Ag + Zn (NO3)3

5. In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?

a) Lead sulphate (insoluble)

(b) Lead acetate

(c) Ammonium nitrate

(d) Potassium sulphate

Ans:(a) Lead sulphate (insoluble)

6. The brown gas evolved on heating of copper nitrate is

(a) O2

(b) NO2

(c) N2

(d) NO

Ans:(b) NO2 

7. Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is:

(a) 1: 1

(b) 2:1

(c) 4:1

(d) 1:2

Ans:(b) 2:1

8. A substance ‘X’ is used in white-washing and is obtained by heating limestone in the absence of air. Identify ‘X’.

(a) CaOCl2

(b) Ca (OH)2

(c) CaO

(d) CaCO3

Ans: (c) CaO 

9. 2HNO3 + Ca (OH)2 → Ca (NO3)2 + 2H2O; is an example of

(i) displacement reaction

(ii) double displacement reaction

(iii) neutralisation reaction

(iv) combination reaction.

(a) (i) and (ii)

(b) (ii) and (iii)

(c) (iii) and (iv)

(d) (i) and (iv)

Ans:(b) (ii) and (iii) 

10. A substance X which is a group 2 element is used intensively in the cement industry. This element is present in bones also. On treatment with water, it forms a solution which turns red litmus blue. Element X is(a) Cu(b) Ca(c)Na

    (d) Al

    Ans: (b) Ca 

Short Answer Type Questions-I (2 Marks)

1. You might have noted that when copper powder is heated in a China dish, the reddish brown surface of copper powder becomes coated with a black substance.

(AI 2019)

(a) Why is this black substance formed?

(b) What is the black substance?

(c) Write the chemical equation of the reaction that takes place.

(d) How can the black coating on the surface be turned reddish brown?

2. Define a combination reaction. Give one example of a combination reaction which is also exothermic.

(a) A solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed. Write the chemical reaction involved and also mention the type of the chemical reaction.

(b) Ferrous sulphate when heated, decomposes with the evolution of a gas having a characteristic odour of burning sulphur. Write the chemical reaction involved and identify the type of reaction.

(Board Term I, 2016)

4. What is observed when carbon dioxide gas is passed through lime water.

(i) For a short duration

(ii) For long duration?

Also, write the chemical equations for the reaction involved.

[Board Term I, 2016]

5. Lead nitrate solution is added to a test tube containing potassium iodide solution.

(a) Write the name and colour of the compound precipitated.

(b) Write the balanced chemical equation for the reaction involved.

(c) Name the type of this reaction justifying your answer.

(2020)

6. Name the type of chemical reaction represented by the following equation:

(Board Term I, 2016)

(i) CaO + H2O → Ca(OH)2

(ii) 3BaCl2 + Al2(SO4)3 → 2AlCl3 + 3BaSO4

(iii) FeSO4​→HeatFe2​O3​+SO2​+SO3​

7. 2 g of silver chloride is taken in a China dish and the China dish is placed in sunlight for some time. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical reaction.

(Delhi 2019)

8. List four observations that help us to determine whether a chemical reaction has taken place.

[Board Term-I, 2012]

9. Identify the type of reactions taking place in each of the following cases and write the balanced chemical equation for the reactions.

(a) Zinc reacts with silver nitrate to produce zinc nitrate and silver.

(b) Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.

(Delhi 2019)

10. i) Can a displacement reaction be a redox reaction? Explain with the help of an

example.?

1. ii) Identify the substances that are oxidised and the substances that are reduced in the

following reactions.

(Board Term I, 2015)

(a) Fe2O3 + 2Al → Al2O3 + 2Fe

(b) 2PbO + C → 2Pb + CO2