Identify the major product of the reaction when the given compound is hydrolyzed and heated strongly.

Match List-$I$ with List-$II$.
List-$I$:
$(a)$ $\text{Benzene} \xrightarrow[\text{CuCl}]{\text{CO, HCl, Anhyd. AlCl}_3} \text{Benzaldehyde}$
$(b)$ $R-CO-CH_3 + NaOX \rightarrow$
$(c)$ $R-CH_2-OH + R'COOH \xrightarrow{\text{Conc. H}_2\text{SO}_4}$
$(d)$ $R-CH_2COOH \xrightarrow[(ii) H_2O]{(i) X_2/\text{Red P}} R-CH(X)COOH$
List-$II$:
$(i)$ $\text{Hell-Volhard-Zelinsky reaction}$
(ii) $\text{Gattermann-Koch reaction}$
(iii) $\text{Haloform reaction}$
(iv) $\text{Esterification}$
Choose the correct answer from the options given below.

Consider the following reaction:
$\text{Propanal} + \text{Methanal}$ $\xrightarrow[\text{(ii)}\Delta, \text{(iii)}\text{NaCN}, \text{(iv)}\text{H}_3\text{O}^+]{\text{(i)}\text{dil. NaOH}} \text{Product } B (C_5H_8O_3)$
The correct statement for product $B$ is:

Identify $Z$ in the following reaction sequence:
$CH_3COONH_4$ $\xrightarrow{\Delta} X$ $\xrightarrow{P_2O_5} Y$ $\xrightarrow{H_2O/H^+} Z$

$(i) \ F_3CCOOH$
$(ii) \ CH_3COOH$
$(iii) \ C_6H_5COOH$
$(iv) \ CH_3CH_2COOH$
Correct order of $pK_a$ value is:

Which of the following has highly acidic hydrogen?