Question

how do we know a chemical reaction has taken place​

Answer 1

Answer:

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.

Answer 2

QUESTION :-

how do we know a chemical reaction has taken place

ANSWER :-

While we observe the following things, we can conclude that a chemical reaction has taken place.

• A change that changes state and colour of substance.
• A change that releases heat energy
• A change that liberates a gas