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What mass of urea be dissolved in 171 g ...

What mass of urea be dissolved in `171 g` of water so as to decrease the vapour pressure of water by `5%`?

A

`15 g`

B

`20 g`

C

`25 g`

D

`30 g`

Text Solution

Verified by Experts

The correct Answer is:
D
`(DeltaP)/P_(A)^(@)=chi_(B)=0.05` (given)
`0.05=n_(B)/(n_(B) + n_(A)) = n_(B)/(n_(B)+(171/18))`
`rArr n_(B) =0.5 rArr W_("urea")=0.5 xx 60 = 30 g`
`["Urea":NH_(2)CONH_(2)]`
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