In which of the following reactions will a resonance-stabilized product be formed?

Which of the following is not true in case of reaction with heated copper at $300 \ ^oC$?

An organic compound $(A)$ reacts with sodium metal to form $(B)$. When $(A)$ is heated with concentrated $H_2SO_4$,it forms diethyl ether. What are $(A)$ and $(B)$ respectively?

The conversion of ethyl alcohol to acetaldehyde is an example of what?

$CH_3 CH_2 OH$ $\xrightarrow{Cl_2} CH_3 CHO$ $\xrightarrow{3 Cl_2} Cl_3 CCHO$. In the above reactions,the role of $Cl_2$ in step-$1$ and step-$2$ respectively is:

$A$ 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.