Question

State whether a physical change is reversible or irreversible.

Answer 1

A physical change is a reversible change i.e., the change can be reversed to bring the substance that has undergone change back to its original form or state.

• Example: Suppose Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ undergoes physical change from ice to liquid form by melting. This liquid form can be converted back to ice form by freezing. This is how the physical change has been reversed.

Physical change: A change in which no new substance is formed and there is no change in the chemical composition of the substance undergoing the change.

• It is a temporary change.
• It is a reversible change as most of the time, the substance can be brought back to its original state.
• Physical properties like hardness, colour, etc. change during a physical change.
• Energy is neither consumed nor released as chemical bonds are not involved in physical change.
• Examples: Conversion of Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ from solid to liquid form, melting of the wax.