- A
- B
- C
- D
Solution:
Concept- For solution A, toluene and benzene have the identical mole fractions, or 0.5 in each case.Toluene has the following partial pressure in a vapour phase:
Here, XT stands for the mole fraction of toluene in the liquid phase, while 
stands for the vapour pressure of pure toluene.Now, the partial pressure of benzene in a vapour phase is:
In this case, XB stands for the mole fraction of pure benzene in the liquid phase, and 
stands for the vapour pressure of pure benzene.Therefore, total pressure in case of solution A becomes:
The toluene and benzene masses in solution B are equal.Toluene has a molar mass of 92.14 g/mol and benzene has a molar mass of 78.11 g/mol.
Let's assume that the solution mixture contains 78.11 g of benzene and 78.11 g of toluene.
This equates to 0.847 moles of toluene and 1 mole of benzene.
Toluene has a mole fraction of 0.4588 and benzene has a mole fraction of 0.5412.
Toluene has the following partial pressure in the vapour phase:
Here, XT stands for the mole fraction of toluene in the liquid phase, while stands for the vapour pressure of pure toluene.Benzene's partial pressure in the vapour phase is:
Here, the terms XB, or the mole fraction of benzene in the liquid phase, and , or the vapour pressure of pure benzene, are used.As a result, the overall pressure is:
Thus, the value of ratio i.e 
Hence, the correct answer is option (1).
