Q$2.$ a$)$ Prove that: $\frac{P{V}_c}{T_c}=\frac{3}{8}R?$ Find the critical temperature and critical pressure of the gas?

Q$3.($a$)$ Starting from the main KMT equation show that $\sqrt[\phantom{2}]{\frac{?}{\text{b}\text{a}\text{r}}(u{)}^2}=H_{\text{m}\text{a}\text{r}}=\sqrt[\phantom{2}]{\frac{3RT}{U}}?$