Question: What is the vapor pressure of a solution containing 1 mole of non-volatile solute in 3 moles of solvent if the vapor pressure of the pure solvent is 100 mmHg?

Options:

1. 75 mmHg
2. 100 mmHg
3. 25 mmHg
4. 50 mmHg

Correct Answer: 75 mmHg

Solution:

Using Raoult\'s law, P_solution = X_solvent * P°_solvent. X_solvent = 3/(1+3) = 0.75, so P_solution = 0.75 * 100 mmHg = 75 mmHg.