Question

A hydrocarbon X has molecular formula $C_8{H}_{18}$. Substitution of a hydrogen of X by bromine atom gives one single bromoalkane. Hence, compound X is

• A. 2, 2, 3, 3-Tetramethylbutane
• B. 2, 3, 4-Trimethylpentane
• C. 2, 5-Dimethylhexane
• D. None of the above

Answer 1

The correct option is A 2, 2, 3, 3-Tetramethylbutane

The order of substitution of hydrogen in alkane is,

tertiary hydrogen > secondary hydrogen > primary hydrogen

Option (a) has primary and quaternary carbon atom, but quaternary carbon atom has no hydrogen to be removed. So we need to consider as this molecule contains only primary carbon atoms. So it will result in single monobromo alkane.

Option (b) has primary and tertiary carbon atom. So both can undergo reaction and results in two derivatives.

Option (c) has primary, secondary and tertiary carbon atoms. So all three can undergo reaction and will result in three derivatives.

Hence, the correct answer is option (a).