Ethylene glycol is used as an antifreeze in a cold climate. Mass of ethylene glycol which should be added to 4 kg of water to prevent it from freezing at ?6°C will be: (Kf for water = 1.86 Kg/mol and molar mass of ethylene glycol = 62 kg/mol)

? T f = k f . m 

for ethylene glycol in aq. solution

  $$\begin{gathered} ? T f = k f w m o l . w t × 1000 w t . o f s o l v e n t \\ 6 = 1 . 86 x w x 1000 62 x 4000 \end{gathered}$$

=> w = 800 g

So, the weight of solute should be more than 800 g.