On mixing, heptane and octane form an ideal solution. At `373K` the vapour pressure of the two liquid components (heptane and octane) are `105 kPa` and `kPa` respectively. Vapour pressure of the solution obtained by mixing `25.0` of heptane and `35g` of octane will be (molar mass of heptane `= 100 g mol^(-1)` and of octane `= 114 g mol^(-1))`:-

Options

A. 96.2kPa
B. 144.5kPa
C. 72.0kPa
D. 36.1kPa

Answer

C

Explanation

`n_("heptane")=(25)/(100)=1/(4)`
`n_("octane")=(35)/(114)`
`P_("solution")=((1)/(4))/((1)/(4)+(35)/(114))xx105+((35)/114)/((1)/(4)+(35)/(114))xx45=72 KPa`