Why is heat evolved or absorbed in a chemical reaction ?

In the presence of a catalyst, the heat evolved or absorbed during the reaction:

In the presence of a catalyst, the heat evolved or absorbed during the reaction:

In the presence of a catalyst, the heat evolved or absorbed during the reaction ………. .

The total amount of heat evolved or absorbed in a reaction depends upon the number of steps in which the reaction takes place.

Evaporation of water is: a process in which heat is neither evolved nor absorbed a process accompanied by chemical reaction an exothermic change an endothermic change.

State which type of chemical reactions proceed with - a. Evolution of heat energy b. Absorption of heat energy. State in each of the following reactions whether heat is evolved or absorbed - i. Water is added to quicklime ii. Two neutral gases on passage through an electric arc give niric oxide iii. Two neutral gases combine to give - a basic gas.

A gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write the balanced chemical equation of the reaction involved.

Energy is either absorbed or evolved during a chemical change.