Nucleophiles, such as ammonia and its derivatives \(H_2N-Z\) add to the carbonyl group of aldehydes and ketones. The reaction is reversible and catalyzed by acid. The equilibrium favours the product formation due to rapid dehydration of the intermediate to form \(-C=N-Z\), where, \(Z =\) Alkyl, aryl, \(OH\), \(NH_2\), \(C_6H_5NH\), \(NHCONH_2\), etc.

What happens when acetone reacts with semicarbazide? 

Acetone semicarbazone

The correct answer is option 1. Acetone semicarbazone.

When acetone reacts with semicarbazide, it forms acetone semicarbazone.

The carbonyl group of acetone (\( \text{C=O} \)) reacts with the semicarbazide to form a semicarbazone. The reaction involves the nucleophilic attack of the nitrogen on the carbonyl carbon, followed by the elimination of water.

The product of this reaction is acetone semicarbazone, which is characterized by the formation of the \( \text{C=N} \) bond between the acetone and semicarbazide.

When acetone reacts with semicarbazide, the product formed is acetone semicarbazone. Therefore, the correct answer is: Acetone semicarbazone.