Identify compounds $X$ and $Y$ in the following reaction: $CH_3COOH + X$ $\xrightarrow{H^+} Y$ $\xrightarrow{H_2, Pd} 2C_2H_5OH$

Which of the following is the correct order of decarboxylation of $\beta$-keto carboxylate anion?

The desired product $X$ $(\text{Ph-C(Me)(Ph)-COOH})$ can be prepared by reacting the major product of the reactions in List-$I$ with one or more appropriate reagents in List-$II$. (Given,order of migratory aptitude: $\text{aryl} > \text{alkyl} > \text{hydrogen}$)
| List-$I$ | List-$II$ |
| :--- | :--- |
| $P$. $\text{Ph}_2\text{C(OH)-C(OH)Me}_2 + \text{H}_2\text{SO}_4$ | $1$. $\text{I}_2, \text{NaOH}$ |
| $Q$. $\text{Ph}_2\text{C(NH}_2\text{)-CH(OH)Me} + \text{HNO}_2$ | $2$. $[\text{Ag(NH}_3)_2]\text{OH}$ |
| $R$. $\text{PhC(OH)(Me)-C(OH)(Ph)Me} + \text{H}_2\text{SO}_4$ | $3$. $\text{Fehling solution}$ |
| $S$. $\text{Ph}_2\text{C(Br)-CH(OH)Me} + \text{AgNO}_3$ | $4$. $\text{HCHO, NaOH}$ |
| | $5$. $\text{NaOBr}$ |

The product $(X)$ of the reaction is:

In the following reactions,what are $B$ and $X$ respectively?
$C_2H_5MgBr$ $\xrightarrow{ClCN} C_2H_5CN$ $\xrightarrow{H_3O^+} B$
$CH_3COCH_3$ $\xrightarrow[NaOH]{I_2} X + CHI_3$ $\xrightarrow{Ag} Y$
$C_6H_5NH_2$ $\xrightarrow[HCl]{NaNO_2} P$ $\xrightarrow{CuCN} Q$ $\xrightarrow{+4H} R$

The increasing order of the acidity of the following carboxylic acids is: