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

Which reaction is incorrectly written?

Identify the product $C$ in the following reaction sequence:
$1$-bromo-$4$-chlorobenzene $+ Mg (1 \text{ mole})$ $\xrightarrow{THF} A$ $\xrightarrow{CO_2} B$ $\xrightarrow{H^+} C$

Benzoyl chloride is prepared from benzoic acid by:

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)?

$A \xrightarrow[\begin{smallmatrix} (ii) CN^{-} \\ (iii) H_{2}O/H^{+} \end{smallmatrix}]{(1) Cl_{2}, \Delta }$ $4-$Bromophenyl acetic acid.
In the above reaction '$A$' is ....