Concept:The addition of hydrogen cyanide (\( HCN \)) to a carbonyl compound yields a cyanohydrin. By examining the alkyl groups on the central carbon of the product, we can deduce the original carbonyl reactant.
Solution:- The product given is \( (CH_3)_2C(OH)CN \).
- In a cyanohydrin, the central carbon was originally the carbonyl carbon (\( C=O \)).
- By removing the \( -OH \) proton and the \( -CN \) group to reform the \( C=O \) bond, we are left with the two groups attached to that carbon: two methyl groups (\( CH_3 \)).
- The carbonyl compound consisting of a carbonyl group bonded to two methyl groups is Acetone (\( CH_3COCH_3 \)).
Why other options are incorrect:If option A (2-butanone) were used, the product would have one ethyl and one methyl group. Option C is an alcohol, which doesn't react with HCN. Option D is an aldehyde, which would yield a cyanohydrin with an ethyl group.
Quality & Fidelity Assurance:
Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.