B$)$ A mixture of H$2($g$)$ and N$2($g$)$ has a density of $0\mathrm{.}216$ g$/$Litre at $300$K and at a pressure of$66661\mathrm{.}2$ pa$.$ Consider both H$2($g$)$ and N$2($g$)$ as ideal gases$\mathrm{.}1)$ Calculate the total number of moles of the mixture of H$2($g$)$ and N$2($g$),$ i$.$e$,$ ntotal?