What is chain isomerism? Explain by giving an example.

(N/A) When two or more compounds have the same molecular formula but different carbon skeletons (i.e.,different branching in the carbon chain),they are referred to as chain isomers,and the phenomenon is termed as chain isomerism.
For example,$C_{5}H_{12}$ (Pentane) represents three chain isomers:
$(i)$ $CH_{3}CH_{2}CH_{2}CH_{2}CH_{3}$ : Pentane
$(ii)$ $CH_{3}-CH(CH_{3})-CH_{2}CH_{3}$ : Isopentane ($2$-methylbutane)
$(iii)$ $C(CH_{3})_{4}$ : Neopentane ($2,2$-dimethylpropane)