The IUPAC name of neo-Pentylbromide is

The correct answer is Option (3) → 1-Bromo-2,2-dimethylpropane

The common names of the \( \ce{C5H11} \)– groups show how the carbon skeleton is branched, while the IUPAC name uses the longest chain containing the carbon bearing the halogen, numbered so that the halogen gets the lowest locant:

• n-Pentyl bromide: \( \ce{CH3CH2CH2CH2CH2Br} \) = 1-bromopentane

• Isopentyl bromide: \( \ce{(CH3)2CHCH2CH2Br} \) = 1-bromo-3-methylbutane

• tert-Pentyl bromide: \( \ce{CH3CH2C(CH3)2Br} \) = 2-bromo-2-methylbutane

• Neopentyl bromide: \( \ce{(CH3)3C-CH2Br} \) = 1-bromo-2,2-dimethylpropane

In neopentyl bromide, the \( \ce{CH2Br} \) carbon is attached to a carbon carrying three methyl groups. The longest chain through the \( \ce{CH2Br} \) carbon has three carbons (propane). Numbering from the \( \ce{CH2Br} \) end puts Br on C-1 and the two extra methyl groups on C-2:

    ¹CH₂Br–²C(CH₃)₂–³CH₃

So the IUPAC name of neopentyl bromide is 1-bromo-2,2-dimethylpropane.

NCERT (2026-27 edition):
Nomenclature – …