A student mixes two chemicals in a test tube. She notices that the mixture starts to bubble and the test tube feels very warm. The student most likely concludes that the mixture is-
F. a chemical reaction that happened too quickly.
G. an endothermic reaction that absorbed thermal energy.
H. an exothermic reaction that released thermal energy.
J. not a chemical reaction.

H. an exothermic reaction that released thermal energy.

Explanation:

The student will most conclude that this is a chemical reaction in which thermal energy is released to the environment.

Such reactions accompanied by the release of thermal energy are exothermic reactions.

For endothermic reactions, heat is absorbed. At the end of the reaction, the system is cold.

the answer is 75.0%.