Identify the major product formed from the sequence of reactions given below:
$C_6H_5NH_2$ $\xrightarrow[(ii) Cu_2Cl_2]{(i) NaNO_2/HCl, 273 K}$ $\xrightarrow{(iii) Na/dry ether} \text{Product}$

Alkyl halide $\xrightarrow[\text{Ether}]{Mg}$ Grignard Reagent $\xrightarrow{H_2O}$ Propane,then alkyl halide may be :-

When $but-3-en-2-ol$ reacts with aqueous $HBr$,the product formed is:

Match the reactions in Column-$I$ with their mechanisms in Column-$II$.

Column-$I$ (Reaction)	Column-$II$ (Mechanism)
$(A)$ $OH^- + CH_3Cl \to HOCH_3 + Cl^-$	$(1)$ $S_N2$ mechanism
$(B)$ $(CH_3)_3CBr + OH^- \to (CH_3)_3COH + Br^-$	$(2)$ $S_E2$ aromatic
$(C)$ $CH_3CH_2Br \xrightarrow[ethanol]{KOH} CH_2 = CH_2$	$(3)$ $S_N1$ mechanism
$(D)$ $C_6H_6 + Br_2 \xrightarrow{Fe} C_6H_5Br + HBr$	$(4)$ $\beta$-elimination (dehydrohalogenation)

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

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: