A solid is placed in a solution. Which observation most likely indicates that a chemical reaction has occurred?

A.)The size of the solid has rapidly decreased.
B.)The color of the solution has not changed.
C.)The solid has bubbles forming on its surface.
D.)The temperature of the solution stays the same.

C.)The solid has bubbles forming on its surface.

Explanation:

A.)The size of the solid has rapidly decreased.  (this may just mean that it is dissolving).

B.)The color of the solution has not changed.  (no change indicates no reaction).

C.)The solid has bubbles forming on its surface.  (bubbles indicate the release of carbon dioxide, meaning that bonds are being broken.)

D.)The temperature of the solution stays the same. ( temp change actually means that there is a reaction happening).

beta decay is the answer