Arrange the following compounds in increasing order of their reactivity towards $HCN$:
$I$. Acetaldehyde
$II$. Acetone
$III$. Di-tert-butyl ketone
$IV$. Methyl-tert-butyl ketone

Consider the following reaction sequence:
$4\text{-aminobenzonitrile}$ $\xrightarrow[(ii) H_2O]{(i) AlH(i-Bu)_2} 'A'$ $\xrightarrow[dil. NaOH, \Delta]{CH_3CHO} B$
The product $B$ is?

Consider the following reaction,where:
$(A)$ The change in the functional group and
$(B)$ The corresponding change in the hybridization from the starting material to the final product are:
$CH_3-C \equiv N \xrightarrow[(ii) \ HI + \text{Red } P]{(i) \ SnCl_2, HCl / H_3O^{+}}$

The major product formed in the following reaction is:

Identify the reagents $X$ and $Y$ in the following reaction sequence:
$CH_3COCl \xrightarrow{X} CH_3CH_2OH$
$CH_3COCl \xrightarrow{Y} CH_3CHO$

The rate of hydrate formation for the given compounds is: