Nitration of which among the following compounds yields cyclonite?

What are $A, B$ and $C$ in the following reaction?
$Ar-N_2^+ BF_4^- \xrightarrow{NaNO_2, \Delta, Cu} A + B + C$

Which of the following compounds can be obtained by an azo coupling reaction?

When acetamide is treated with $HNO_2,$ the gas evolved is:

Which one will not give alcohol on reduction with $LiAlH_4$?

Assertion $(A)$: $-NH_2$ group of aniline is ortho,para directing in electrophilic substitutions.
Reason $(R)$: $-NH_2$ group stabilises the arenium ion formed by the ortho,para attack of the electrophile.
The correct answer is