In the reaction shown below,the $o/p$ ratio will be highest when:
$C_6H_5R + HNO_3 \xrightarrow{H_2SO_4} o-\text{nitro-substituted product} + p-\text{nitro-substituted product}$

The two reactions involved in the conversion of benzene diazonium chloride to diphenyl are respectively:

Identify the best suitable reagent for the following reaction.

In chlorobenzene,the $-Cl$ group is deactivating; however,it still undergoes electrophilic aromatic substitution reactions. Column-$(I)$ contains the reagents and Column-$(II)$ contains the products. Match Column-$(I)$ with Column-$(II)$.
| Column-$(I)$ (Reagents) | Column-$(II)$ (Products) |
| :--- | :--- |
| $(A)$ $Cl_2$ / anhydrous $AlCl_3$ | $(i)$ $1$-chloro-$2$-methylbenzene + $1$-chloro-$4$-methylbenzene |
| $(B)$ conc. $HNO_3$ + conc. $H_2SO_4$ | $(ii)$ $2$-chlorobenzenesulfonic acid + $4$-chlorobenzenesulfonic acid |
| $(C)$ conc. $H_2SO_4$ and heat | $(iii)$ $1,2$-dichlorobenzene + $1,4$-dichlorobenzene |
| $(D)$ $CH_3COCl$ in presence of anhydrous $AlCl_3$ | $(iv)$ $2$-chloroacetophenone + $4$-chloroacetophenone |
| | $(v)$ $1$-chloro-$2$-nitrobenzene + $1$-chloro-$4$-nitrobenzene |

Give chemical reactions for the following conversions:
$(1)$ Nitrobenzene from phenol
$(2)$ $p$-methylacetophenone from benzene

For the reaction shown below,identify the major product $A$ and the reaction mechanism $R$:
$m$-bromoanisole $\xrightarrow{NaNH_2} A, R$