A gaseous mixture contains ethylene: $30\mathrm{.}6\%,$ benzene: $24\mathrm{.}5\%,O_2$:$1\mathrm{.}3\%,$ ethane: $25\%,N_2$:$3\mathrm{.}1\%$ and methane: $15\mathrm{.}5\%$ in volume basis. Estimate the composition in mole $\%,$ weight $\%,$ average molecular weight and density