Question

the amount of heat given off or absorbed by a chemical reaction is called

an exothermic reaction
a joule
the product of pressure and volume
the change in enthalpy

Explanation:

• An exothermic reaction is a type of reaction that releases heat, not the amount of heat itself.
• A Joule is a unit of energy, not the term for the heat in a reaction.
• The product of pressure and volume ($PV$) is not directly related to the heat of a chemical reaction.
• Enthalpy change ($\Delta H$) specifically represents the heat given off or absorbed by a chemical reaction under constant pressure.

Answer:

the change in enthalpy