Dry distillation of calcium acetate and calcium formate forms:

The reaction of benzene with $CO$ and $HCl$ in the presence of anhydrous $AlCl_3$ gives a compound $X$. $X$ can also be obtained from which of the following reactions?

Ketones $(R-C(=O)-R_1)$ where $R = R_1 = \text{alkyl group}$. It can be obtained in one step by:

Which reagent from the following is used for the preparation of aliphatic aldehyde from nitriles?

The reaction is given as follows:
$Ph-CO-N(CH_3)(OCH_3) + 2CH_3MgBr \xrightarrow{H_3O^+} (P)$
Product $(P)$ is:

On heating glycerol with conc. $H_2SO_4$,a compound is obtained which has a bad odour. The compound is: