The correct decreasing order of the basic strength is

Which of the following amines gives a yellow oily liquid with $HNO_{2}$?

Consider the following four compounds $I, II, III,$ and $IV$.
Choose the correct statement$(s)$.
$(A)$ The order of basicity is $II > I > III > IV$.
$(B)$ The magnitude of $pK_b$ difference between $I$ and $II$ is more than that between $III$ and $IV$.
$(C)$ Resonance effect is more in $III$ than in $IV$.
$(D)$ Steric effect makes compound $IV$ more basic than $III$.

In the reaction $C_6H_5NH_2 + HCl + NaNO_2 \to X$,the product $X$ is:

The amine $A$,when treated with nitrous acid,gives a yellow oily substance. The amine $A$ is

Aniline,when diazotized in cold and then treated with $N,N$-dimethylaniline,gives a coloured product. Its structure would be: