Although chlorobenzene does not undergo the Ullmann reaction,the presence of which group at the $o-$ and $p-$ positions of chlorobenzene makes it possible to undergo the Ullmann reaction?

Out of $o$- and $p$-dibromobenzene,which one has a higher melting point and why?

Which of the following compounds has the most difficulty in breaking the $C-Cl$ bond?

Which of the following has the highest melting point?

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 |

The following reaction is: