Question

how can you say that burning of a substance is an Irreversible change?

Answer 1

Answer:

During burning of incense stick, some pleasant smelling gases are produced (which go into the air) and ash is left behind. We cannot recombine the gases and the ash to get back the original incense stick. So, this is a change which cannot be reversed. Thus, the burning of an incense stick is an irreversible change.

Answer 2

Answer:

we can say that because after burning anything it will be not reversed means it will not become as the original