MHTCET 11 Apr 2026 Shift 2 Paper

Concept:Alkenes and alkynes add bromine across their multiple bonds and decolourise $\mathrm{Br}_2$ water, while aromatic benzene does not.Explanation:Bromine water has a reddish-brown colour due to dissolved $\mathrm{Br}_2$.Ethene, ethyne, and cyclohexene contain carbon-carbon multiple bonds.They readily undergo addition with bromine, which removes the reddish-brown colour.For example, ethene reacts as: $\mathrm{CH}_2=\mathrm{CH}_2+\mathrm{Br}_2 \rightarrow \mathrm{CH}_2\mathrm{Br}-\mathrm{CH}_2\mathrm{Br}$.Ethyne and cyclohexene behave similarly due to their $\pi$ bonds.Benzene has a stable aromatic ring with delocalised $\pi$ electrons.It does not undergo ordinary addition with bromine water, as that would disturb its aromatic stability.Benzene reacts with bromine only in the presence of a catalyst like $\mathrm{FeBr}_3$, not with bromine water.Therefore, benzene does not decolourise $\mathrm{Br}_2$ water.Answer:Option C: Benzene