Question

in investigation 2, an exothermic reaction occurred as energy was released. what is the best evidence that an exothermic reaction occurred in the beaker?
a the bubbling stopped.
b there was a change in the color.
c the mass decreased.
d there was an increase in temperature.

Explanation:

An exothermic reaction releases energy in the form of heat. A temperature increase in the beaker indicates heat release, which is characteristic of an exothermic reaction. Bubbling stopping (A) relates to reaction completion, color change (B) is a physical property change, and mass decrease (C) could be due to gas release (not specific to exothermic).

Answer:

D. There was an increase in temperature.