Question

How many of the following are not ambiguous? Pentane, Neopentane, sec-Butanol, sec-Pentanol

Answer 1

Answer: 3

Three of the given four names have only one possible structure. The fourth one, sec-pentanol has three possible structures and hence it can not be ambiguous. Three structures possible for sec-pentancl are as follows:
$\mathrm{CH}{}_3\stackrel{\underset{|}{\mathrm{O}}\mathrm{H}}{\mathrm{C}}\mathrm{HCH}{}_2\mathrm{CH}{}_2\mathrm{CH}{}_3$,
$\mathrm{CH}{}_3\stackrel{\underset{|}{\mathrm{O}}\mathrm{H}}{\mathrm{C}}\mathrm{HCH}(\mathrm{CH}{}_3){}_2$ and
$\mathrm{CH}{}_3\mathrm{CH}{}_2\stackrel{\underset{|}{\mathrm{O}}\mathrm{H}}{\mathrm{C}}\mathrm{HCH}{}_2\mathrm{CH}{}_3$