\(\because \,\frac{W}{M} > \frac{w}{m}\) \( \Rightarrow \frac{{640 - 600}}{{640}}\)
\( = \frac{w}{m} \times \frac{M}{W} \Rightarrow \frac{{40}}{{640}} = \frac{{2.175 \times 78}}{{m \times 39.08}}\) ;
\(m = \frac{{2.175 \times 78}}{{39.08}} \times \frac{{640}}{{40}}\)
\(m = 69.45\).
($CHCl_3$ નુ મોલર દળ $= 35.5\, g\, mol^{-1}$ )
$[K_f \,(H_2O)= 1.86\,K\,kg\,mol^{-1}$ ; $K_b\,(H_2O) = 0.52\,K\,kg\,mol^{-1} ]$