Nucleophilic addition reactions

Why this is asked: Reactivity toward nucleophilic addition runs aldehydes above ketones, and an aryl group directly on the carbonyl carbon lowers it further still, since the ring donates electron density into the C=O by resonance and makes that carbon less electrophilic. That steric-plus-electronic combination is what "arrange by reactivity toward HCN/NaHSO₃" questions are actually testing, not a memorised list.

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