Question

Which of the following is a chemical change:
A. Burning of coal
B. Dissolving sugar in water
C. Dissolving salt in water
D. Melting of ice

Answer 1

Hint: You should know that a chemical change occurs when one chemical substance is transformed into one or more different substances, such as when iron becomes rust.
Now try to identify the chemical change among all.

Complete step by step answer:
Now, let’s discuss the correct answer to this question -

If the chemical composition is changing in a process then it is a chemical change and if the chemical composition is remaining the same in the process, then it is a physical change.

Burning of coal is an example of chemical change because here coal in the presence of oxygen turns into carbon dioxide and water. These are completely different compounds.
Dissolving sugar in water and dissolving salt in water are not examples of chemical change as there is no formation of new substances.
Melting of ice is also not an example of chemical change because the formula of the substance present here remains the same i.e ${ H }_{ 2 }O$.

Therefore, we can conclude that the correct answer to this question is option A.

Additional information -
We should also know that when iron comes in contact with air and moisture it reacts with it and forms a brownish layer on its surface due to the formation of its oxides. This is called the rusting of iron. It is a chemical change since the new substance is formed.

Note: We should be aware of the fact that chemical processes, in general, are not reversible or we can say irreversible except for a few chemical reactions.