Answer:

(a)An exothermic reaction occurs when energy is discharged from the system into the environment.

An endothermic reaction occurs when energy is taken from the environment in the form of heat.

(b) The reaction for thermal decomposition of limestone which is an example of an endothermic reaction is as follows:

CaCO₃(s)→CaO (s)+CO₂(g)

Burning of fuel is an example for exothermic reaction.

C₈H₁₈(l)+25O₂(g)→16CO₂(g)+18H₂O (g)+heat

(c) (i) and (iv) are exothermic reaction. (ii),(iii),(v) are endothermic reactions