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NEET levelSingle correct optionDifficulty 1 of 3o1112

In the addition of $HCN$ to a ketone, a small amount of $KCN$ or $NaOH$ is added mainly because it

Aconverts the carbonyl oxygen into a better leaving group
Braises the concentration of the nucleophile $CN X^{-}$
Cforms an enolate of the ketone
Dreduces the carbonyl group to an alcohol

Answer: B

HCN

is a weak acid (pKa about 9.2), so pure

HCN

supplies very little

CN X^{-}

. Base shifts

HCN H X^{+} + CN X^{-}

to the right, and

CN X^{-}

is the attacking nucleophile.

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