Aldehydes, Ketones and Carboxylic Acids Part 3

Concept:Cross aldol condensation yields multiple products only when both aldehydes contain $\alpha$-hydrogen atoms. Semicarbazide forms semicarbazones with both aldehydes and ketones, but aldehydes are more reactive than ketones.Explanation:Statement I: Cross aldol between two different aldehydes does not always give four products. If one aldehyde lacks $\alpha$-hydrogens (e.g., benzaldehyde), it cannot form a self-aldol product. Thus, the number of products depends on the presence of $\alpha$-hydrogens. Controlled conditions can also reduce product mixture. Hence, Statement I is false. Statement II: Semicarbazide reacts with both $\mathrm{C}_6\mathrm{H}_5\mathrm{CHO}$ (benzaldehyde) and $\mathrm{C}_6\mathrm{H}_5\mathrm{COCH}_3$ (acetophenone). Aldehydes (benzaldehyde) undergo condensation faster than ketones (acetophenone) under optimum pH. So the condensation product forms preferentially with benzaldehyde, not only with acetophenone. Hence, Statement II is false.Answer:Both Statement I and Statement II are false. Correct option: B.