Question

Rusting of an article made up of iron is called:

• A. Corrosion and it is a physical as well as chemical change
• B. Dissolution and it is a physical change
• C. Corrosion and it is a chemical change
• D. Dissolution and it is a chemical change

Answer 1

The correct option is C

Corrosion and it is a chemical change

Explanation:

Reaction of moist air with Iron: Rusting

• When iron is exposed to moist air it reacts with the oxygen present in the air to form ferrous oxide.
• This is a brown flaky layer coating formed on iron and causes the destruction of iron.
• This formation is known as rust, and the process is known as corrosion.

$\underset{\mathrm{Iron}}{\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\stackrel{\mathrm{moisture}}{\to }\underset{\mathrm{Rust}}{{\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O}\left(\mathrm{s}\right)}$

Chemical change:

• A chemical change is a permanent change and cannot be reversed by simple physical methods.
• One or more new substances are formed with composition and properties different from the original substances.
• For example, cooking of food, rusting of iron, etc.

Therefore, option C is correct.