Question

List two observations that could be evidence of a chemical reaction.

Answer 1

Emission of heat or light, or a color change.

Answer 2

1) Smell or odour

2) Colour change

Step-by-step explanation:

1) Smell or odour

Example: Add HCl to a FeS solution. There will be a strong odor of H2S

2) Colour change

Example : NaOH and KMnO4 solution to a river water sample. There will be a colour change to brown.