Which of the following picture depicts the chemical reaction?

The correct answer is:

• A chemical change occurs when one substance combines with another to form a new substance. This is known as chemical synthesis or chemical decomposition into two or more different substances. These processes are called chemical reactions and can usually be reversed only by further chemical reactions.
• In the picture, we see the burning of wood. The wood when burnt changes to ashes and soot. This can't be reversed. New substances are formed.