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# The order of decreasing stability of the carbanions $(CH_3)_3 C^-(I) ; (CH_3)_2CH^{-1}(II) ; CH_3CH_2^{-}(III); C_6H_5CH_2^{-} (IV)$ is

$(a)\;I > II > III > IV \\ (b)\;IV > III > II > I \\(c)\; IV > I > II > III \\ (d)\;I > II > IV > III$

Can you answer this question?

Hyperconjugation decreases the heat of hydrogenation.
Lesser the heat of hydrogenation lesser is the internal energy and more is the stability of the system.
Hyperconjugation effect increases in the order.
$(CH_3)_3C^{-} < (CH_3)_2 CH^{-} < CH_3CH_2^- < C_6H_5 CH_{2}^{-}$
Therefore $IV > III > II > I$
Hence b is the correct answer.
answered Feb 26, 2014 by