Question

a solid and a liquid are mixed in a test tube. which of the following observations would indicate that a chemical reaction occurred between them? select all that apply a the mixture changes color to a deep blue. b the solid settles to the bottom of the mixture. c the mixture starts to fizz as a gas is released. d the test tube becomes colder as the substances are mixed.

Explanation:

Color change (a), gas evolution (c), and temperature change (d) are common signs of chemical reactions. A solid settling to the bottom (b) is a physical - separation process, not a sign of a chemical reaction.

Answer:

A. The mixture changes color to a deep blue.
C. The mixture starts to fizz as a gas is released.
D. The test tube becomes colder as the substances are mixed.