1.

The vapour pressure of pure benzene and pure toluene at a particular temperature are 100 mm and 50 mm repectively. The mole fration of benzene in the vapour phase in contact with equimolar solution os benzene and toluene is:

Answer»

0.67
0.75
0.33
0.5

Solution :For equimole solutions, `X_(B)=X_(f)=0.5`
`P_(B)=X_(B)xxP_(B)^(@)=0.5xx100=500mm`
`P_(T)=X_(T)xxP_(T)=0.5xx50-25 mm`
`"TOTAL vapour pressure "(P_("Total")=75MM`
Mole fraction of benzene in the vapour PHASE=
`P_(B)/_("Total")=50/75=2/3=0.67.`


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