Select the correct statements about carbocation stability.

A $(CH X_{3}) X_{3} C X^{+}$ is more stable than $(CH X_{3}) X_{2} CH X^{+}$
B $CH X_{2} = CH - CH X_{2} X^{+}$ is more stable than $CH X_{3} CH X_{2} CH X_{2} X^{+}$
C $CH X_{3} X^{+}$ is more stable than $CH X_{3} CH X_{2} X^{+}$
D $CH X_{2} = CH X^{+}$ is more stable than $CH X_{3} CH X_{2} X^{+}$

Answer: A, B

Tertiary is more stable than secondary because of more hyperconjugation and +I effect. The allyl cation is resonance stabilised, unlike primary propyl. Ethyl is more stable than methyl. The vinyl cation is less stable than ethyl because the positive charge sits on an sp carbon (more electronegative, poorly hyperconjugated). Hence only statements 1 and 2 are correct.

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Select the correct statements about carbocation stability.

Answer: A, B

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