Calculate the percentage of nitrogen in ammonium nitrate $\left({\mathrm{NH}}_4{\mathrm{NO}}_3\right)$.

The compound $\mathrm{A}$ has $26.7\% \mathrm{C},71.1\%$ $\mathrm{O}$ and $2.2\%\mathrm{H}$. Determine the empirical formula of $\mathrm{A}$.

The compound $\mathrm{A}$ has $26.7\% \mathrm{C},71.1\%$ $\mathrm{O}$ and $2.2\%\mathrm{H}$. If the relative molecular mass of $\mathrm{A}$ is $90$, what is the molecular formula of $\mathrm{A}$?

Find the total percentage of oxygen in magnesium nitrate crystals.

$\mathrm{Mg}{\left({\mathrm{NO}}_3\right)}_2.6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{H}=1 \mathrm{u}, \mathrm{N}=14 \mathrm{u}, \mathrm{O}=16 \mathrm{u}, \mathrm{Mg}=24 \mathrm{u}\right)$

The empirical formula of a compound is ${\mathrm{C}}_2{\mathrm{H}}_5$. It has a vapour density of $29$. Determine the relative molecular mass of the compound and hence its molecular formula.

Solid ammonium dichromate (relative molecular mass $252$) decomposes as under:

${\left({\mathrm{NH}}_4\right)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7\to {\mathrm{N}}_2+{\mathrm{Cr}}_2{\mathrm{O}}_3+4{\mathrm{H}}_2\mathrm{O}$

If $63 \mathrm{g}$ of ammonium dichromate decomposes, what will be the loss of the mass?

Solid ammonium dichromate (relative molecular mass 252) decomposes as under:
$({\mathrm{NH}}_4{)}_2{\mathrm{Cr}}_2{\mathrm{O}}_7\to {\mathrm{N}}_2+{\mathrm{Cr}}_2{\mathrm{O}}_3+4{\mathrm{H}}_2\mathrm{O}$

Calculate the mass of $63\mathrm{g}$of chromium $\left[\mathrm{III}\right]$ oxide formed at the same time.