What is obtained when glycerol is heated with oxalic acid at $110\,^{\circ}C$?

In the reaction,$x$,$y$ and $z$ are

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

Give the reaction methods to prepare carboxylic acid from amide compounds.

Which reaction is suitable for the preparation of $\alpha$-chloroacetic acid?

Glacial acetic acid is obtained by