Class 10 Science Chapter 1 Practice Question Answers - Chemical Reactions & Equations

Very Short Answer Questions

1. Is it possible to have combustion without oxygen?

2. Can a double displacement reaction be a redox reaction?

3. What happens when a strip of zinc is dipped in a copper sulphate solution?

4. Is copper more reactive than iron? Give a reaction in support of your answer _

5. In which type of reaction does an exchange of partner takes place?

6. (Based on activities)

Why a dilute acid is added to water during electrolysis of water?

7. Name the product obtained on cathode during electrolysis of water

8. Is the volume of gases produced during electrolysis of water is same? If not than what is the ratio in between them?

9. What will happen if silver bromide is kept for some time in sunlight?

10. Write names of three metals which do not corrode?

11. Name two antioxidants which are usually added to fat and oil containing foods to prevent rancidity.

Short Answer Questions :_

1. What do you mean by a precipitation reaction?

2. Why should a magnesium ribbon be cleaned before burning in air?

3. Write a balanced chemical equation with symbols for the following reactions _

(i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.

(ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

4. Write the balanced equation for the following chemical reactions.

(i) Hydrogen + chlorine → Hydrogen chloride.

(ii) Barium chloride + Aluminium Sulphate → Barium sulphate + Aluminium chloride.

(iii) Sodium + water ¾® Sodium hydroxide + Hydrogen.

5. How can you say that respiration is an exothermic process?

Name two biochemical reaction which are exothermic.

6. Why blue colour of copper sulphate solution becomes faded when iron fillings are added to it?

7. What happens when copper turnings are added to silver nitrate solution?

8. Why the solution of silver nitrate becomes blue in colour after some time when copper turnings are added to it?

9. A solution of a substance 'X' is used for white washing _

(i) Name the substance 'X' and write the formula.

(ii) Write the reaction of the above substance 'X' with water.

10. Why is the amount of gas double in one of the test tube during the electrolytic decomposition of water? Name the gas?

11. When a green iron salt is heated strongly, its colour finally changes to black and odour of burning sulphur is given out.

(i) Name the iron salt

(ii) Name the type of reaction that takes place during the heating of iron salt.

(iii) Write the chemical equation for the reaction involved.

12. Write one equation each for decomposition reactions where energy is supplied by heat, light and electricity.

13. What is the difference between displacement and double displacement reactions? Write equations for these reactions.

14. Classify each of the following reactions as combination, decomposition, displacement or double displacement reaction.

(i) H₂ + Cl₂ → 2HCl

(ii) 2KClO₃ 2KCl + 3O₂

(iii) Zn + CuSO₄ → ZnSO₄ + Cu

Blue Colour less

(iv) 2Pb(NO₃)₂ 2PbO_(s) + 4NO₂(g) + O₂(g)

(v) NaOH + HCl → NaCl + H₂O

(vi) BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl

(vii) CaO + CO₂ → CaCO₃

(viii) CaCO₃ CaO + CO₂

(ix) 2KI + Cl₂ → 2KCl + I₂

ANSWER KEY

Chemical reaction & equation

Very short answer type

1. No 2. No 3. Blue colour of solution fade up.

4. No, because iron is more reactive metal than copper.

Fe + CuSO₄ ¾® FeSO₄ + Cu

5. Double displacement reaction. 6. To increase the ionization of water.

7. Hydrogen gas 8. No, H₂ : O₂ (2 : 1)

9. Photochemical reaction takes place.

2AgBr ¾® 2Ag(s) + Br₂(g)

10. Silver, Gold, Platinum.

11. (a) BHA (Butylated Hydroxy Anisole)

(b) BHT (Butylated Hydroxy Toluene)
 

Short Answer

14. (i) Combination reaction (ii) Decomposition reaction (iii) Displacement reaction

(iv) Decomposition reaction] (v) In double displacement reaction  Neutralization reaction

(vi) Double displacement reaction (vii) Combination reaction (viii) Decomposition reaction

(ix) Displacement reaction (x) Decomposition reaction