Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

Chain isomers possess the same molecular formula and functional groups but differ in the arrangement of their carbon skeleton (parent chain length or branching).

(A) is correct: It compares a straight 5-carbon chain (pentanenitrile) with a branched 4-carbon parent chain (3-methylbutanenitrile).

(B) is correct: It compares a 4-carbon parent chain (2-methylbutanenitrile) with a 3-carbon parent chain (2,2-dimethylpropanenitrile).

(C) is correct: Both alkenes share the formula $C_6{H}_{12}$ but have differently branched carbon skeletons.

(D) is incorrect: These are functional isomers because one contains a cyanide ($-CN$) group and the other contains an isocyanide ($-NC$) group.