Which of the following compounds is a tertiary alkyl halide?

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 $.............. \ g \ mol^{-1}$.

How many isomers are possible for the compound with the molecular formula $C_2BrClFI$?

Product $A$ is

What is the product of the following reaction?

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: