Question

if a powdered solid were mixed with a liquid which of the following observations would most clearly indicate a chemical reaction was occurring? a the mixture gets colder. b the mixture gets warmer. c the solid settles to the bottom of the mixture. d the mixture starts fizzing and releasing gas.

Explanation:

A chemical reaction often results in the formation of a new substance. Fizzing and gas - release indicate the formation of a gaseous product, a strong sign of a chemical reaction. Temperature changes (a and b) can also occur in physical processes like dissolving some salts (endothermic or exothermic dissolutions). A solid settling to the bottom (c) is a physical separation process, not a chemical reaction.

Answer:

d. The mixture starts fizzing and releasing gas.