What is obtained when oxalic acid is dehydrated in the presence of concentrated $H_2SO_4$?

The decreasing order of the rate of alkaline hydrolysis for the following esters is:
$I: C_6H_5COOC_2H_5$
$II: p-Cl-C_6H_4COOC_2H_5$
$III: p-NO_2-C_6H_4COOC_2H_5$
$IV: p-CH_3O-C_6H_4COOC_2H_5$

The product $(A)$ is:

$R-CO-OR' \xrightarrow{LiAlH_4} B + C$. Both $B$ and $C$ give a positive iodoform test. $R$ and $R'$ can be:

Identify $X$ and $Y$ in the following reactions:

Consider the following molecules $:$
$(p) \ CH_3-CH_2-COCl$
$(q) \ CH_3-CH_2-CO-O-COCH_3$
$(r) \ CH_3-CH_2-CO-OCH_2-CH_3$
$(s) \ CH_3-CH_2-CONH_2$
The correct order of rate of hydrolysis is $:$