At which value of $n$ does the formation of a six-membered ring take place in the following reaction?
$Br-(CH_2)_n-CH_2-Br + CH_2(CO_2Et)_2 \xrightarrow{NaOEt, EtOH} \text{cyclic product}$

$CH_3-C(=O)-OH$ $\xrightarrow{NaH^{14}CO_3} (A) (\text{gas})$ $\xrightarrow[(ii) H_3O^{+}]{(i) PhMgBr} (B)$
$CH_3-S(=O)_2-OH$ $\xrightarrow{NaH^{14}CO_3} (C) (\text{gas})$ $\xrightarrow[(ii) H_3O^{+}]{(i) PhMgBr} (D)$
Product $(B)$ and $(D)$ in the above reaction are:

$CH_3-CO-CH_2-CH_2-CH_2-CO_2H \xrightarrow[(ii) H_2O, H^+]{(i) NaBH_4} ?$
What will be the final product of this transformation?

Choose the correct option$(s)$ for the following reaction sequence. Consider $Q$,$R$ and $S$ as major products.

Compound $A$ was prepared by oxidation of compound $B$ with alkaline $KMnO_4$. Compound $A$ on reduction with lithium aluminium hydride $(LiAlH_4)$ gets converted back to compound $B$. When compound $A$ is heated with compound $B$ in the presence of $H_2SO_4$,it produces a fruity smell of compound $C$. To which family do the compounds $A$,$B$,and $C$ belong?

The product $(X)$ of the reaction is: