Question

The following graph is obtained for an ideal solution containing a non-volatile solute. \(x\)- and \(y\)-axes represent, respectively

• A. mole fraction of solute, vapour pressure of solute
• B. mole fraction of solvent, vapour pressure of solution
• C. mole fraction of solute, vapour pressure of solution
• D. concentration of solution, vapour pressure of solution

Hint:

In ideal solutions with non-volatile solutes, only the solvent contributes to vapour pressure. So, vapour pressure vs mole fraction of **solvent** gives a straight line.

Answer 1

The Correct Option is B

Step 1: Understand the nature of the solution

• The solution is ideal and contains a non-volatile solute.
• Therefore, only the solvent contributes to the vapour pressure.

Step 2: Recall Raoult’s law

\[ P_{\text{solution}} = X_{\text{solvent}} . P^0_{\text{solvent}} \] This means vapour pressure of the solution varies linearly with the mole fraction of solvent.

Step 3: Interpret the graph

• The graph is a straight line, indicating a linear relation.
• Therefore, the \(x\)-axis must be the mole fraction of solvent.
• The \(y\)-axis must be the vapour pressure of solution.

Final Answer:

mole fraction of solvent, vapour pressure of solution