Select the cation(s) which are stabilised by both resonance and hyperconjugation.

A $(CH X_{3}) X_{2} C X^{+} - CH = CH X_{2}$
B $C X_{6} H X_{5} - CH X^{+} - CH X_{3}$
C $CH X_{2} = CH - CH X_{2} X^{+}$
D $(CH X_{3}) X_{3} C X^{+}$

Answer: A, B

(CH X_{3}) X_{2} C X^{+} - CH = CH X_{2}

has a vinyl group (resonance) and two methyl groups with sp3 C-H (hyperconjugation). 1-Phenylethyl has a ring and a methyl group. The allyl cation has no sp3 alpha C-H bonds, and the tert-butyl cation has no pi system.

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Select the cation(s) which are stabilised by both resonance and hyperconjugation.

Answer: A, B

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