The reaction of cyclohexanone with semicarbazide ( NH₂NHCONH₂ ) to form a semicarbazone is an example of a/an _____(i)_____ reaction, and the nitrogen atom that acts as the nucleophile is the _____(ii)_____. Choose the correct option to fill in the blanks.

Step-by-step solution

The reaction of aldehydes and ketones with ammonia derivatives (such as semicarbazide) is a nucleophilic addition-elimination reaction, where initial nucleophilic addition is followed by the elimination of a water molecule to form a > C=N-Z bond. Semicarbazide has two types of -NH₂ groups. The -NH₂ group attached directly to the carbonyl group ( -C=O ) is involved in resonance with the carbonyl pi bond, which delocalizes its lone pair of electrons and significantly reduces its nucleophilicity. The terminal -NH₂ gro