Decarboxylation of isobutyric acid gives .....

The product $P$ in the following reaction is:
$PhCHO + (CH_3CH_2CO)_2O \xrightarrow{CH_3CH_2COONa \text{ (anhydrous)}} P$

Consider the following sequence of reactions:
$2\text{-benzylbenzoic acid}$ $\xrightarrow{SOCl_2} A$ $\xrightarrow[2. H_3O^+]{1. AlCl_3} B$ $\xrightarrow{Zn-Hg, \text{conc. } HCl, \text{heat}} C$
The end product $(C)$ is:

Which of the following compounds undergoes decarboxylation upon gentle heating?

Formaldehyde and formic acid can be distinguished using

Which among the following compounds has the highest boiling point?