Benzotrichloride reacts with milk of lime to form

$A$ methyl group attached to a benzene ring can be oxidized to a carboxyl group by reacting with:

The major product in the following reaction is:

Compare the two methods shown for the preparation of carboxylic acids.
Method $1$: $RBr$ $\xrightarrow[diethyl \ ether]{Mg} RMgBr$ $\xrightarrow[2. \ H_3O^{+}]{1. \ CO_2} RCO_2H$
Method $2$: $RBr$ $\xrightarrow{NaCN} RCN$ $\xrightarrow[heat]{H_2O, HCl} RCO_2H$
Which one of the following statements correctly describes this conversion for the given substrate ($1$-bromoadamantane)?

When toluene is treated with $KMnO_4$,what is produced?

Describe the method for the preparation of carboxylic acids from nitrogen-containing compounds (nitriles) with suitable examples.