The number of structural isomers of ${\mathrm{C}}_7{\mathrm{H}}_9\mathrm{N}$ that satisfies both the below given conditions is______.

i. Should have a benzene ring
ii. Should have an amine group

How many of the following compounds can be categorized as secondary amines?

Propan-$2$-amine, diphenylamine, $N$-isopropylaniline, dibenzylamine, ethylmethylamine, $N$-methylisopropylamine, $p$-tert-butylaniline.

Reaction of aniline with acetic anhydride in presence of pyridine yields acetic acid and product $\text{'}\mathrm{X}\text{'}$.

What is the total number of groups from the following, present in the compound $\text{'}\mathrm{X}\text{'}$?

If molar mass of compound B is $\mathrm{x}$, then find $\frac{\mathrm{x}}{2}$

How many among the following would form a coloured dye on treatemnt with ${\mathrm{NaNO}}_2$ in dil.$HCl$ followed by addition to an alkaline solution of $\beta$-naphthol?

Acetylation of aniline with acetic anhydride in presence of pyridine yields acetic acid and product $\text{'}\mathrm{X}\text{'}$.

How many of the below given groups present in the compound $\text{'}\mathrm{X}\text{'}$?