1.

A solution of urea ( mol. =56 g "mol"^(-1) ) boils at 100.18^(@)C at the atmospheric pressure. If K_(f) and K_(b) for water are 1.86 and 0.512 K kg "mol"^(-1) respectively, then the above solution will freeze at :

Answer»

`0.654^(@)C`
`-0.654^(@)C`
`6.54^(@)C`
`-6.54^(@)C`

SOLUTION :`m=(DeltaT_(F))/(K_(f))=(Delta T_(b))/(K_(b))`
`Delta T_(b)=100.18-100=0.18^(@)`
`:.DeltaT_(f)=(Delta T_(b))/(K_(b))xxK_(f)`
`=(0.18)/(0.512)xx1.86=0.654^(@)`
`:.` FREEZING point of solution `=0-0.654`
`=-0.654^(@)C`


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