$m$-chlorobenzaldehyde on reaction with conc. $KOH$ at room temperature gives

Which of the following compounds is highly reactive towards $HCN$?

Consider the following reaction sequence:
$B \xleftarrow{NaBH_4} CH_2=CH-CHO \xrightarrow{H_2/Pt} A$
Identify $A$ and $B$.

Arrange the following compounds in decreasing order of reactivity towards nucleophilic addition reaction:
$I: HCHO$
$II: CH_3CHO$
$III: CH_3COCH_3$
$IV: PhCOCH_3$

Choose the incorrect statement among the following.
$A$. The reactivity of aromatic aldehydes and ketones is less than that of aliphatic carbonyl compounds towards nucleophilic addition reactions.
$B$. Benzaldehyde does not give Fehling's test.
$C$. The $\alpha$-$H$ atoms in ethanal are acidic in nature.
$D$. $p$-nitro benzaldehyde is less reactive than benzaldehyde towards nucleophilic addition reactions.

$CH_3CHO \xrightarrow{LiAlH_4} CH_3CH_2OH$
Which nucleophile is added in this reaction?