Identify the reagent $R$ used in the following reaction:
$\text{Ketone} \xrightarrow{R} \text{Semicarbazone}$

$A$ compound gives a positive test with $I_2/NaOH$ and is extracted from benzene by $NaHSO_3$. It may be:

Explain aldol condensation and the acidity of the $\alpha$-carbon of aldehydes and ketones. Provide the aldol condensation reactions for $ethanal$ and $propanone$.

Which of the following represents the correct order of reactivity towards nucleophilic addition reactions?

An organic compound $x$ where the molar ratio of $C$, $O$, and $H$ are equal, on treatment with $50\% \ KOH$ under reflux followed by acidification produced $y$. The most likely structure of $y$ is: [Molar mass of $x$ is $58 \ g \ mol^{-1}$]

Given below are two statements:
Statement $I$: $H_2N-CO-CH_2-CH_2-CO-CH_3$ under Clemmensen reduction conditions will give $HOOC-(CH_2)_3-CH_3$.
Statement $II$: $CH_3-CH(CH_3)-CH_2-CH(Cl)-CO-CH_3$ under Wolff-Kishner reduction conditions will give $CH_3-CH(CH_3)-CH_2-CH(Cl)-CH_2-CH_3$.
In the light of the above statements,choose the correct answer from the options given below: