Cherylanne mixes together chemical a and chemical b in a test tube, forming chemical c. the mixture instantly turns cool to the touch. she then adds chemical d, and the reaction becomes hot and explodes. what can be known about this situation?

The sign of the entalphy change

Explanation:

In the first reaction, the potential energy of products is greater than that of the reactants. Hence, the enthalpy change is positive. Heat is absorbed from the surrounding in other to balance the net energy change and this makes the reaction vessel cool to the touch.

This kind of reaction is known as an endothermic reaccion.

In the second reaction,the product formed from the first reaction reacts with the new added reactant. The results yields an exothermic reaction in which heat is released to the surroundings and hence the potential energy of the reactants is greater than that of the products. The enthalpy change here is negative. This kind of reaction is called an exothermic reaction

the answer your looking for is c).