Which among the following compounds is $NOT$ prepared by Sandmeyer's reaction?

In Gattermann reaction,a diazonium group is replaced by $\underline{X}$ using $\underline{Y}$. $\underline{X}$ and $\underline{Y}$ are:
$\underline{X} \quad \underline{Y}$

Toluene is nitrated and the resulting product is reduced with tin and hydrochloric acid. The product so obtained is diazotised and then heated with cuprous bromide. The reaction mixture so formed contains

Identify the reagent involved in the Sandmeyer reaction.

The conversion of benzene diazonium chloride to bromobenzene can be accomplished by

The reaction in which copper$(I)$ salt is used to replace nitrogen in diazonium salt is called,