From which of the following substances is acetone prepared?

Conversion of benzene to acetophenone can be brought about by

In the reaction $CH_3CN + CH_3MgI \to A \xrightarrow{H_2O/H^{+}} B$,the compound $B$ is

In the following reaction sequence,identify the compound $Z$ if the starting material is toluene $(C_6H_5CH_3)$:
$C_6H_5CH_3 \xrightarrow{CrO_2Cl_2 / CS_2, H_3O^+} Z$

In the following reaction,product $P$ is: $RCOCl \xrightarrow{H_2, Pd-BaSO_4} P$

Identify $Z$ in the following sequence of reactions.
$C_2H_4Br_2$ $\xrightarrow[\text{(ii) } NaNH_2]{\text{(i) alc- } KOH} X$ $\xrightarrow[\text{Red hot}]{\text{Fe tube, } 873 \ K} Y$ $\xrightarrow[\Delta]{\left(CH_3CO\right)_2O / \text{Anhyd-} AlCl_3} Z$