c
ઉત્કલન બિંદુ \(C_6H_6\) \(= 80 + 273 = 353\,k,\) ગુપ્ત ઉષ્મા \((L_v)\) \(= 90\,cal/g\)

\(\Delta T\) \(= 80.175 - 80 = 0.175\), \(w = 1\,g\),  \(W = 83.4\,g\)

\({K_{b\,}} = \,\,\frac{{R{T^2}}}{{1000{L_v}}}\)

અથવા \({K_b}\,\, = \,\,\frac{{2\,\, \times \,\,353\,\, \times \,353}}{{1000\,\, \times \,\,90}}\,\,\)

\( = \,\,2.769\,\,K\,\,mo{l^{ - 1}}\,\,kg\)

હવે \(,\,\,\Delta T\,\, = \,\,\frac{{{K_b}\,\, \times \,\,1000\,\, \times \,\,w}}{{m\,\, \times \,\,83.4}}\)  

\(\therefore \,\,m\,\, = \,\,189.79\)