What are $X$ and $Y$ in the following reaction sequence?
$Toluene$ $\xrightarrow{X} Benzaldehyde$ $\xrightarrow{HNO_3 + H_2SO_4, 273-283 \ K} Y$

The product obtained in the following transformation is:

Given below are two statements: Statement $I$: The condensation reaction between $CH_{3} - CH = O$ and $H_{2}N - NH - C(=O) - NH_{2}$ under optimum pH will produce $CH_{3} - CH = N - N(H) - C(=O) - NH_{2}$. Statement $II$: The molecule, $Ph - CH(OH)(OCH_{3})$ will generate $Ph - CH = O$ in the presence of dilute acid. In the light of the above statements, choose the correct answer from the options given below:

The reaction of ethyl methyl ketone with $Cl_2$ / excess $OH^{-}$ gives the following major product:

Which one of the following compounds is the best choice for being prepared by an efficient mixed aldol addition reaction?

The best reagent to carry out the following conversion is:
$3$-hydroxyethylcyclopentane-$1$-carbaldehyde $\rightarrow$ $1$-ethyl-$3$-methylcyclopentane (with a hydroxy group on the ethyl side chain).
(Note: The image shows the reduction of an aldehyde group $-CHO$ to a methyl group $-CH_3$ while keeping the secondary alcohol $-CH(OH)CH_3$ intact.)