Question

What are the observable changes that occur when a chemical reaction take place'?​

Answer 1

A chemical reaction is usually accompanied by easily observed physical effects, such as the emission of heat and light, the formation of a precipitate, the evolution of gas, or a color change. Absolute confirmation of a chemical change can only be validated by chemical analysis of the products!

Answer 2

Answer:

such as the emission of heat and light, the formation of a precipitate, the evolution of gas, or a color change.