Which of the following compounds will give a pair of enantiomers upon nucleophilic substitution reaction with a hydroxideion?

2-bromobutane

The correct answer is Option (1) → 2-bromobutane

Analyze each compound

1. 2-bromobutane

• Structure: CH₃–CHBr–CH₂–CH₃
• C-2 is attached to: CH₃, CH₂CH₃, H, Br → chiral
• SN2 reaction with OH⁻ → inversion → pair of enantiomers possible
   Yes

1. 2-bromo-2-methylbutane

• Structure: (CH₃)₂CBr–CH₂–CH₃
• C-2 attached to: 2 CH₃, CH₂CH₃, Br → not 4 different groups → not chiral
   No

1. 1-bromo-3-methylbutane

• Br on primary carbon (C-1) → only 3 different groups (H, CH₂, CH₂CH(CH₃)₂?)
• C-1 not chiral →  No

1. 1-bromobutane

• Primary carbon, not chiral →  No