$HCHO$ was treated with a reagent $X$. The product formed upon hydrolysis in the presence of an acid gave $C_{2}H_{5}OH$. The reagent $X$ is

The structure of $(R)$ is:

Match the following:

$A$. Lucas reagent	$I$. $SnCl_2 + HCl$
$B$. Clemmensen reagent	$II$. $[Ag(NH_3)_2]^+$
$C$. Tollen's reagent	$III$. Anhydrous $ZnCl_2 + conc. HCl$
$D$. Stephen reagent	$IV$. $Zn-Hg/HCl$

$C_6H_5CHO + HCN \to C_6H_5-CH(OH)-CN$. The product would be

The reagent used in the Wolff-Kishner reduction is

Consider the following reaction sequence:
$\text{But-2-ene}$ $\xrightarrow{\text{ozonolysis}} X$ $\xrightarrow[(ii) H_3O^+]{(i) CH_3MgBr} Y$ $\xrightarrow[573 \ K]{Cu} Z$
The correct statements about $Z$ are:
$I$. It gives yellow precipitate with $I_2$ and $NaOH$ solution.
$II$. It undergoes disproportionation reaction in the presence of concentrated $NaOH$ solution.
$III$. It undergoes Wolff-Kishner reduction.
$IV$. It forms red precipitate with Fehling's reagent.