Which of the following pairs are not functional group isomers?
(i) II and III
(ii) II and IV
(iii) I and IV
(iv) I and II
The answer is the option (i) and (iii)
Explanation: Isomerism is a phenomenon in which two compounds have the exact same molecular formula, but the different structural formula and such compounds are called isomers, and Functional isomers have same molecular formula but a different functional group.