Important Questions for CBSE Class 10 Science Chapter 1

Important Questions for CBSE Class 10 Science Chapter 1: Here you will find the important questions and solutions for Chapter 1 of Chemical Reactions and Equations for Class 10 Chemistry. These significant queries relate to the most recent Class 10 Chemistry Syllabus and are based on the CBSE board curriculum. Students can quickly review all of the concepts presented in the chapter and be ready for the Class 10 Annual Examinations by practising these crucial Class 10 questions.

Important Questions for CBSE Class 10 Science Chapter 1 with Answers


Q.1 The shiny finish of the wall after whitewash is because of.
a) Calcium oxide
b) Calcium hydroxide
c) Calcium Carbonate
d) Calcium phosphate

Q.2 Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during the electrolysis of water is
a) 1:1
b) 2:1
c) 4:1
d) 1:2

Q.3 Which of the following statements about the given reaction are correct:
3Fe(s) + 4H2O (g)→ Fe2O3(s) + 4H₂(g)
i) Iron metal is getting oxidized
ii) Water is getting reduced
iii) Water is acting as a reducing agent
iv) Water is acting as an oxidizing agent
a) (i), (ii) and (iii)
b) (iii) and (iv)
c) (i), (ii) and (iv)
d) (ii) and (iv)

Q.4 In order to prevent the spoilage of potato chips, they are packed in plastic bags containing the gas
a) Cl₂
b) O₂
c) N₂
d) H₂

Q.5 The process of respiration is –
a) an oxidation reaction which is endothermic
b) a reduction reaction which is exothermic
c) a combination reaction which is endothermic
d) an oxidation reaction which is exothermic

Q.6 Burning of Methane is an example of
I. Exothermic reaction
II. Combustion reaction
III. Decomposition reaction
a. I only
b. II only
c. I and II
d. I and III

Q.7 A solution of substance X is used for whitewashing, the substance X is
a. Calcium oxide
b. Calcium hydroxide
c. Calcium carbonate
d. Calcium chloride

Q.8 When iron nails are dipped into Copper Sulphate solution the colour of the Copper Sulphate solution changes from
a. Green to blue
c. Green to colourless
b. Blue to green
d. Blue to colourless

Q.9 The given Chemical reaction is an example of
Zn+CuSO4 → ZnSO4 + Cu
a. Combination reaction
c. Decomposition reaction
b. Displacement reaction
d. Double displacement reaction

Q.10 The balanced equation for the given chemical reaction is
Hydrogen + Chlorine → Hydrogen Chloride
a. H₂+Cl₂→ 2HCI
c. H₂+ Cl₂ →HCI
b. H + Cl→ HCI
d. none of the above

Q.11 Give an example of a double displacement reaction.

Q.12 Name the reducing agent in the given chemical reaction
3MnO2 + 4Al →3Mn+2Al2O3

Q.13 Name the brown-coloured gas that evolved when lead nitrate crystals are heated in a dry test tube.

Q.14 Give reasons-
a) Silver chloride is stored in dark-coloured bottles.
b) Copper vessel loses shine when exposed to air
c) Iron displaces copper from copper sulphate solution.

Q.15 What changes do you observe in iron nails and the colour of copper sulphate solution, if iron nails are dipped in CuSO4 solution for some time?

Q.16 Identify the chemical change:
Melting of ice or conversion of milk into curd.

Q.17 Why is respiration considered an exothermic reaction?

Q.18 Why do copper vessels lose shine when exposed to air?

Q.19 When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an example of a
(a) combination reaction
(b) displacement reaction
(c) decomposition reaction
(d) double displacement reaction.

Q.20 In a double displacements reaction such as the reaction between sodium sulphate solution and barium chloride solution :
(A) exchange of atoms takes place
(B) exchange of ions takes place
(C) a precipitate is produced
(D) an insoluble salt is produced
The correct option is
(a) (B) and (D)
(b) (A) and (C)
(c) only (B)
(d) (B), (C) and (D)

Q.21 Potato chips manufacturers fill the packet of chips with nitrogen gas. Why?

Q.22 Why do we store silver chloride in dark-coloured bottles in labs?

Q.23 Write a chemical equation of a double displacement reaction.

Q.24 N₂+ 3H2 → 2NH3, name the type of reaction.

Q.25 What happens when milk is left open at room temperature during summers?

Q.26 What happens when quick lime is added to water?


Q.1 Define combination reaction. Give two examples of combination reactions, which are exothermic in nature.

Q.2 What is decomposition reaction? Explain with the help of an example.

Q.3 Name and state the law which is kept in mind when we balance a chemical equation.

Q.4 Give one example of each:
(a) Chemical reaction showing the evolution of gas.
(b) Change in colour of a substance during a chemical reaction.
(c) Chemical reaction showing change in temperature.

Q.5 A small amount of Ferrous sulphate is heated in hard glass tube.
(a) Write the chemical equation.
(b) What type of reaction is taking place or Name the type of reaction.

Q.6 What happens when Zn strip is dipped in CuSO4 solution?
Give an equation and identify the type of reaction.

Q.7 A small amount of Ferrous sulphate is heated in hard glass tube.
(a) Write the chemical equation.
(b) What type of reaction is taking place or Name the type of reaction.

Q.8 What happens when Zn strip is dipped in CuSO, solution?
Give equation and identify the type of reaction.

Q.9 What is redox reaction? Write down a chemical reaction representing it.

Q.10 In electrolysis of water:
(a) Name the gas collected at cathode and anode respectively.
(b) Why is volume of one gas collected at one electrode is double of another?
(c) Why is it necessary to add few drops of dil. H₂SO, to water before electrolysis?

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