Question

What are indications that a chemical reaction has occurred?

Answer 1

See below.

Explanation:

The indications of a chemical change or a chemical reaction has occurred are the following:

1. Formation of a precipitation.
2. Change in color.
3. Evolution of gas.
4. Evolution or absorption of heat.
5. Odor.

Here is a video that features experimental procedures on physical and chemical change:
Lab Experiment #2: Physical & Chemical Changes.