Consider the following reaction: CaCO3 + Heat → CaO + CO2 This reaction is: ___

(A) an exothermic decomposition.

(B) an endothermic decomposition.

(C) an exothermic combination.

(D) an endothermic combination.

The correct answer is option B.

Explanation:

Exothermic reactions are are those reaction which heat evolved and released into the surroundings. Due to this release of heat temperature of the surrounding increases.

Endothermic reactions are are those reaction which heat absorbed from the surroundings. Due to this absorption of heat temperature of the surrounding decreases.

Decomposition reaction : the reaction in which single compound broke down into its smaller compounds or elements.

Combination reaction : The reaction which two or more compounds combine together to give single compound.

In the given reaction, heat is provided or it is absorbed by the calcium carbonate to break down into calcium oxide and carbon dioxide.

Hence, endothermic decomposition reaction.