Question

Identify the processes which are wrongly paired.

• A. Sublimation - Physical change
• B. Crystallisation - Chemical change
• C. Condensation - Physical change
• D. Corrosion - Physical change

Answer 1

Answer: (B), (D)

The correct options are
B Crystallisation - Chemical change
D Corrosion - Physical change

When a material undergoes a change in shape, size or state without undergoing any change in its chemical composition, it is called a physical change. Changes which leads to change in the composition of substance and formation of new substance are called chemical changes.

During sublimation, crystallisation and condensation, the state of the substance changes but the chemical composition of the substance undergoing the change remains the same. Corrosion is a chemical change because during corrosion, the metals are converted generally into their oxide or sulphide form forming a new substance.