Aqua regia is a mixture of .

$\left(\mathrm{A}\right) \mathrm{Conc}.{\mathrm{HNO}}_3(1 \mathrm{part}) +\mathrm{Conc}.\mathrm{HCl}(3 \mathrm{parts})$/ $\left(\mathrm{B}\right) \mathrm{Conc}. {\mathrm{H}}_2{\mathrm{SO}}_4(1 \mathrm{part})+\mathrm{Conc}.\mathrm{HCl}(3 \mathrm{parts})$.

Enter your correct answer as A or B.

The formula of acidic nitrogen hydride is _____.

$\left(\mathrm{A}\right) {\mathrm{N}}_3\mathrm{H}/\left(\mathrm{B}\right) {\mathrm{NH}}_3$.

Enter your correct answer as A or B.

_____ and $\mathrm{NO}$ are neutral oxides of nitrogen.

$\left(\mathrm{A}\right) {\mathrm{N}}_2\mathrm{O} / \left(\mathrm{B}\right) {\mathrm{NO}}_2$

Enter your correct answer as A or B.

Write the shapes of the hydrides of group $15$ elements. Arrange them in order of decreasing basic strength, increasing bond angle  and decreasing reducing character.

Account for the following observation:

${\mathrm{NH}}_3$ has higher boiling point than ${\mathrm{PH}}_3$