Q.Identify 'X' in the reaction shown: bromobenzene, treated with

Aryl halides react with Mg in dry ether to form an aryl Grignard reagent, which reacts with water (or any active-hydrogen compound) to give the parent arene (hydrocarbon) - here, bromobenzene is converted back to benzene.

Step 1: Bromobenzene reacts with magnesium turnings in dry ether to form the Grignard reagent, phenylmagnesium bromide:

C6H5Br + Mg --(dry ether)--> C6H5MgBr

Step 2: The Grignard reagent is extremely reactive towards any source of active hydrogen (like water); it is protonated/hydrolyzed to give benzene:

C6H5MgBr + H2O --> C6H6 (X = benzene) + Mg(OH)Br

…