Glycerol heated with oxalic acid at $110^\circ C$ to form

Write a method of preparation for carboxylic acid from the oxidation of primary alcohol and aldehyde compounds.

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

How is glacial acetic acid obtained?

Identify product $C$ in the following conversion sequence: $m$-Hydroxybenzaldehyde $\xrightarrow[\text{Protection of } -OH \text{ group}]{C_6H_5CH_2Cl} A$ $\xrightarrow{[O]} B$ $\xrightarrow{\text{deprotection}} C$.

Find product $V$ in the following reaction sequence:
$CH_3-CH(CH_3)-COOH$ $\xrightarrow[H_3O^{+}]{LiAlH_4} I$ $\xrightarrow{PBr_3} II$ $\xrightarrow[ether]{Mg} III$ $\xrightarrow{CO_2} IV$ $\xrightarrow{H_3O^{+}} V$