Identify the major product formed from the following reaction sequence:

Identify the correct order of reactivity for the following pairs towards the respective mechanism:
$(A)$ $S_{N}2$: Isobutyl bromide > tert-Butyl bromide
$(B)$ $S_{N}1$: Benzyl bromide > $2-$Phenylethyl bromide
$(C)$ Electrophilic substitution: Chlorobenzene > $1-$Chloro$-4-$nitrobenzene
$(D)$ Nucleophilic substitution: Bromobenzene < $1-$Bromo$-4-$nitrobenzene
Choose the correct answer from the options given below:

The compound which is $NOT$ formed when a mixture of $n$-butyl bromide and ethyl bromide is treated with sodium metal in the presence of dry ether is:

In the given reaction,$[X]$ will be:

In the following reaction sequence,
$Br-CH_2-CH(Br)-Ph$ $\xrightarrow[2. NaNH_2]{1. Alc. KOH} X$ $\xrightarrow[4. Conc. HNO_3/H_2SO_4]{3. HgSO_4/dil. H_2SO_4, Heat} Y$
$X$ and $Y$ respectively are,

Consider the following sequence of reactions:
Nitrobenzene $\xrightarrow[(ii) NaNO_2, HCl, 0^{\circ}C]{(i) Sn + HCl} \text{Benzenediazonium chloride}$ $\xrightarrow{(iii) Cu_2Cl_2} \text{Chlorobenzene}$ $\xrightarrow{(iv) Na, \text{Ether}} A$
Molar mass of the product formed $(A)$ is $.............. \ g \ mol^{-1}$.