What is the composition of the vapour which is in equilibrium at `30@C` with a benzene-toluene solution with a mole fraction of benzene of (a) `0.400` and (b) `0.600`?
`P_(b)@ = 119` torr ,`P_(t)@ = 37.0` torr

Explanation

To solve the problem, we need to find the composition of the vapor in equilibrium with a benzene-toluene solution at 30°C for two different mole fractions of benzene (XB). We will use Raoult's Law and Dalton's Law of partial pressures.

### Given Data:
- Vapor pressure of pure benzene, \( P^0_B = 119 \, \text{torr} \)
- Vapor pressure of pure toluene, \( P^0_T = 37.0 \, \text{torr} \)

### Part (a): Mole fraction of benzene \( (X_B = 0.400) \)

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