In a chemical cold pack, two substances are kept separate by a divider. when the divider is broken, the substances mix and absorb heat from the surroundings. the chemical cold pack feels cold.

Answer;

-This is an example of endothermic reaction;

Explanation;

-An endothermic reaction is a chemical reaction accompanied by the absorption of heat.  Examples: Dry ice subliming (changing from a solid directly to a gas). On the other hand, an exothermic reaction is a chemical reaction that releases energy by light or heat. The reactants have more energy than the products

1 a

2 d

3 a

4 c

explanation: