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Freezing point of an aqueous solution is...

Freezing point of an aqueous solution is `-0.186^(@)C`. If the values of `K_(b)andK_(f)` of water are respectively 0.52 K kg `mol^(-1)` and 1.86 K kg `mol^(-1)` then the elevation of boiling point of the solution in K is

A

`0.52`

B

`1.04`

C

`1.34`

D

`0.052`

Text Solution

Verified by Experts

The correct Answer is:
D

`because` Freezing point of the aqueous solution
`=-0.186^(@)C`
`therefore` Depression in freezing point,
`DeltaT_(f)=0^(@)C-(-0.186^(@)C)`
`=+0.186^(@)C=+0.186K`
We know that, `DeltaT_(f)=K_(f).m …(i)`
and elevation in boiling piont,
`DeltaT_(b)=K_(b).m ...(ii)`
Eq. (i) Eq. (ii) gives
`(DeltaT_(f))/(DeltaT_(b))=(K_(f))/(K_(b))`
`implies (0.186K)/(DeltaT_(b))=(1.86K kg mol^(-1))/(0.52K kg mol^(-1))`
`DeltaT_(b)=(0.186xx0.52)/(1.86)`
`=0.052K`
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