Which of the following is the structural formula of mesityl oxide?

An alkene $(A)$ $C_{16}H_{16}$ on ozonolysis gives only one product $(B)$ $C_8H_8O$. $(B)$ can also be obtained by the hydrolysis of the product obtained from the reaction between cyanobenzene and $CH_3MgBr$. $(A)$ shows geometrical isomerism and decolourises $Br_2$ water. $(B)$ on treatment with $SeO_2$ produces $(C)$. Which statement is not correct about $(B)$?

An organic compound $(X)$ has an empirical formula $C_4H_8O$. This gives a pale yellow precipitate with iodine in $NaOH$ solution. What is $X$?

The starting material is $CH_3COCH_2CHO$. The reaction sequence is:
$CH_3COCH_2CHO$ $\xrightarrow[{(ii)LiAlH_4}]{{(i)ethylene\,glycol/dry\,HCl}} A$ $\xrightarrow[\Delta ]{H_3O^{+}} B$
What will be $B$?

Base-catalyzed aldol condensation occurs with:

Which pair never represents $X$ and $Y$ in the following reaction?
Reaction: $X \xrightarrow{Y} CHCl_3 + Z$