Chemical Reactions and Equations MCQs | Class 10 Science Chapter 1 Quiz

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

Assertion (A): While equalizing the number of atoms to balance a chemical equation, we alter the formula of the compounds or elements involved in the reaction.

Reason (R): A chemical equation is balanced by making the number of atoms of each element equal on both sides of the arrow.

You are given the solution of lead nitrate. In order to obtain a yellow precipitate you should mix with it a solution of ______.

Assertion (A): In the reaction: MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂

HCl is getting oxidized while MnO₂ is getting reduced.

Reason (R): The process in which oxygen is added to a substance is called oxidation whereas the process in which oxygen is removed from a substance is called reduction.

Assertion (A): A white-washed wall develops a coating of calcium carbonate after a few days.

Reason (R): Calcium oxide on the wall reacts slowly with carbon dioxide in the air.

A small amount of copper powder is heated as shown in the figure.

Which reaction shows the above reaction?

Identify the product which represents the solid state in the above reaction.

Which of the following are exothermic processes?

1. Reaction of water with quick lime
2. Dilution of an acid
3. Evaporation of water
4. Sublimation of camphor (crystals)

Assertion (A): Following is a balanced chemical equation for the action of steam on iron:

3Fe  +  4H₂0 → Fe₃O₄  + 4H₂

Reason (R): The law of conservation of mass holds good for a chemical equation.

The silver chloride is placed under the sunlight as shown in the figure. The color of silver chloride after some time is:

Solid calcium oxide reacts vigorously with water to form calcium hydroxide accompanied by the liberation of heat. This process is called slaking of lime. Which among the following is/are true about slaking of lime?

1. 1. It is an endothermic reaction.

1. 1. It is an exothermic reaction.

1. 1. The pH of the resulting solution will be more than seven.

1. 1. The pH of the resulting solution will be less than seven.

Which of the following statements about the given reaction are correct?

3Fe + 4H₂O → Fe₃O₄ + 4H₂

1. 1. Iron metal is getting oxidized.

1. 1. Water is getting reduced.

1. 1. Water is acting as a reducing agent.

1. 1. Water is acting as an oxidizing agent.

Which of the following reaction(s) is an endothermic reaction?

Sunita takes about 2 g ferrous sulphate crystals in a dry boiling tube and heats the boiling tube over the flame of a burner or spirit lamp as shown in the figure.

The color of crystals after heating is:

Identify the endothermic reaction(s) among the following:

1. 1. 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

1. 1. Na₂CO₃ + 2HCl → 2NaCl + CO₂ + H₂O

1. 1. C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

1. 1. CaCO₃ → CaO + CO₂