Silver Mirror test is given by which one of the following compounds?

Consider the following sequence of reactions.
$C_6H_5COONa$ $\xrightarrow[\Delta]{NaOH/CaO} X$ $\xrightarrow[\text{Anhy. } AlCl_3]{CO/HCl} Y$ $\xrightarrow[NaOH]{\text{conc. }} A + B$.
If $A$ is the reduction product of $Y$,what is $B$?

Match the reactions in Column-$I$ with their products in Column-$II$.
| Column-$I$ (Reagents) | Column-$II$ (Product) |
| :--- | :--- |
| $(A) \ CH_3CHO + 2C_2H_5OH \xrightarrow{HCl_{(g)}} $ | $(i) \ (CH_3)_2C(OCH_2)_2$ |
| $(B) \ CH_3COCH_3 + CH_2OH-CH_2OH \xrightarrow{HCl_{(g)}} $ | $(ii) \ CH_3CH(OH)CN$ |
| $(C) \ CH_3CHO + HCN$ $\xrightarrow{OH^-}$ $\xrightarrow{H_3O^+}$ | $(iii) \ CH_3CH(OC_2H_5)_2$ |
| $(D) \ CH_3CHO + HCN \xrightarrow{OH^-} $ | $(iv) \ CH_3CH(OH)COOH$ |

$A$ compound has a vapour density of $29$. On warming with an aqueous solution of alkali,it gives a yellow precipitate. The compound is

An organic compound '$X$' having molecular formula $C_5H_{10}O$ yields phenylhydrazone and gives negative response to the iodoform test and Tollens' test. It produces $n-$pentane on reduction. '$X$' could be

The aldol condensation of $CH_{3}CHO$ results in the formation of