Question 1 (Board SQP, 2020) - MCQ from Past Year Papers - Chapter 1 Class 10 - Chemical Reactions and Equations

Which of the following reactions is an endothermic  reaction?  

(a) Burning of coal.  

(b) Decomposition of vegetable matter into compost.  

(c) Process of respiration.  

(d) Decomposition of calcium carbonate to form quicklime and carbon dioxide.  

Answer

Here,

• Endothermic Reaction: Endo means in and thermic means heat. In these reactions, heat is absorbed.
• Exothermic Reaction: Exo means out and thermic means heat. In these reactions, heat is released.

Let’s look at the reactions one by one

1. The burning of coal is a combustion reaction in which heat is released. Therefore, it is an exothermic reaction .
2. Decomposition of vegetable matter also leads to the production of heat, so it is an exothermic reaction .
3. Respiration is the breakdown of food to release energy. Therefore, it is an exothermic reaction .
4. Heat is needed to be supplied for the decomposition of calcium carbonate to form quicklime and CO 2 , so it is an endothermic reaction .

So, the correct answer is (d)