JEE Main · 2012 · 29 Apr 2012 · Offline · Hydrocarbons

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Which branched chain isomer of the hydrocarbon with molecular mass 72 u gives only one isomer of mono substituted alky halide ?

(A)Tertiary butyl chloride
(B)Neopentane✓ Correct
(C)Isohexane
(D)Neohexane

Answer: (B)

Solution

A molecular mass of

72

u matches

C_{5} H_{12}

, the pentanes. For only one monosubstituted halide every hydrogen must be equivalent, which happens only in neopentane,

C (C H_{3})_{4}

, whose twelve hydrogens all sit on equivalent methyl groups because of its high symmetry. Replacing any one of them gives the same product, so neopentane is the branched isomer that yields a single monohalide.

JEE Main · 2012 · 29 Apr 2012 · Offline · Single correct option

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