$\because \,\,\Delta {T_b}\,\, = \,\,\frac{{1000K{_b}\,\,w}}{{mW}}$
$\,\,\therefore \,\,0.323\,\, = \,\,\frac{{1000\,\, \times \,\,3.9\,\, \times \,\,0.5143}}{{m\,\, \times \,\,35}}$
$m\,\, = \,\,177.42$
[ઉપયોગ : ${R}=0.083\, {~L}\, bar \,{mol}^{-1} \,{~K}^{-1}$ ]