Which isomer of hexane has only two different sets of structurally equivalent hydrogen atoms?

Options

A. 2,2-dimethylbutane
B. 2-methylpentane
C. 3-methylpentane
D. 2,3-dimethylbutane

Answer

D

Explanation

Draw the complete structural formula of every compound and examine the chemical environment of every H atom:
It has types of replaceable H atoms: primary `(1^@)` and secondary `(2^@)` H atoms.
`overset(1^(@))(C)H_(3)-underset(underset(1^(@))CH_(3))underset(|)(overset(2^(@))(C))H-underset(underset(1^(@))(C)H_(3))underset(|)overset(2^(@))(C)H-overset(1^(@))(C)H_(3)`
It has two types of replaceable H atoms primary `(1^(@))` and secondary `(2^(@))` H atoms.