Tonics in general contain

$A$ toxic compound $A$ when reacted with $NaCN$ in aqueous acidic medium yields an edible cooking component and food preservative $B$. $B$ is converted to $C$ by diborane and can be used as an additive to petrol to reduce emission. $C$ upon reaction with oleum at $140^{\circ} C$ yields an inhalable anesthetic $D$. Identify $A, B, C$ and $D$,respectively.

Arrange the following in order of their reactivity when reacting with $HCl/ZnCl_2$ (Lucas reagent):
$I. CH_3-C(CH_3)_2-OH$
$II. CH_3-CH(CH_3)-OH$
$III. CH_3-CH_2-OH$
$IV. Ph-C(CH_3)_2-OH$

$PCC$ is

Among the compounds $A$ and $B$ with molecular formula $C_9H_{18}O_3$,$A$ has a higher boiling point than $B$. The possible structures of $A$ and $B$ are

Ethyl alcohol on oxidation with $K_2Cr_2O_7$ gives