When dinitrogen pentoxide (${\mathrm{N}}_2{\mathrm{O}}_5,$a white solid) is heated, it decomposes into nitrogen dioxide and oxygen. If a sample of ${\mathrm{N}}_2{\mathrm{O}}_5$, produces $1.6 \mathrm{g} {\mathrm{O}}_2$, then how many grams of ${\mathrm{NO}}_2$ are formed? ${\mathrm{N}}_2{\mathrm{O}}_5\left(\mathrm{s}\right)\stackrel{\mathrm{\Delta }}{\to }{\mathrm{NO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$ (not balanced)
 

$\mathrm{A}+2\mathrm{B}+5\mathrm{C}⟶{\mathrm{AB}}_2\mathrm{C}+2{\mathrm{C}}_2$

When $0.5$ moles of $\mathrm{A}$ and $1.2$ moles of $\mathrm{B}$ were taken $0.8$ moles of ${\mathrm{C}}_2$ were produced. Hence the limiting reagent is:
 

Zinc and hydrochloric acid react according to the reaction:

$\mathrm{Zn}\left(\mathrm{s}\right)+2\mathrm{HCl}\left(\mathrm{aq}\right)⟶{\mathrm{ZnCl}}_2\left(\mathrm{aq}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)$

If $0.30 \mathrm{mole}$ of $\mathrm{Zn}$ is added to hydrochloric acid containing $0.52 \mathrm{mole}$ of $\mathrm{HCl}$, how many moles of ${\mathrm{H}}_2$ are produced?