Which of the following anions is NOT stabilised by resonance?

A $CH X_{3} - CH X_{2} - O X^{-}$
B $C X_{6} H X_{5} - O X^{-}$
C $CH X_{2} = CH - CH X_{2} X^{-}$
D $CH X_{3} - COO X^{-}$

Answer: A

Resonance needs a lone pair or charge adjacent to a pi bond. In ethoxide the charge on oxygen is attached only to sp3 carbon, so it is localised. Acetate, phenoxide and allyl anion each have an adjacent pi bond and are delocalised.

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Which of the following anions is NOT stabilised by resonance?

Answer: A

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