1. CH equiv CH 2. CH ₃ - CH ₃ 3. CH ₂ =CH ₂ 4. CH ₄

Topic: Alkanes: conformations, halogenation mechanism· Hydrocarbons

Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is

1. CH$\equiv$CH

2. CH$_3$$-$CH$_3$

3. CH$_2$=CH$_2$

4. CH$_4$

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Answer: 4. CH$_4$

The alkyl bromide undergoes Wurtz coupling, $\mathrm{2R{-}Br+2Na\to R{-}R+2NaBr}$. The product has twice the carbon count of R, and must be a gas with fewer than four carbons.

Substitution by bromine is typical of alkanes. From $\mathrm{CH_4}$: $\mathrm{CH_3Br}$, then ethane ($\mathrm{C_2H_6}$, a gas). Ethane would give butane (4 C), alkenes and alkynes undergo addition rather than substitution. So A is $\mathrm{CH_4}$.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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Hydrocarbon (A) reacts with bromine by substitution to form an alkyl bromide which by Wurtz reaction is converted to gaseous hydrocarbon containing less than four carbon atoms. (A) is

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