Question

Which of the following is an example of chemical change?

• A. Conversion of steam to water
• B. Rusting of iron
• C. Cutting of wood
• D. Melting of ice candy

Answer 1

The correct option is B Rusting of iron

Rusting of iron is a chemical reaction. When iron rusts, it reacts with oxygen present in water or moisture in the air to create a new compound called iron (III) oxide.
$\text{Fe}\left(s\right)+{\text{O}}_2\left(g\right)\to {\text{Fe}}_2{\text{O}}_3.x{\text{H}}_2\text{O}\left(s\right)$

${\text{Fe}}_2{\text{O}}_3.x{\text{H}}_2\text{O}$ is commonly known as rust and has properties entirely different from that of iron or oxygen.
Other options involve either change in physical state or size.