Exams › NEET › Chemistry

The vapour pressure of a solvent decreased by 10 mm of mercury when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be 20 mm of mercury?

1. 0.8
2. 0.6
3. 0.4
4. 0.2

Correct answer: 0.6

Solution

The decrease in vapour pressure is directly proportional to the mole fraction of the solute. If the mole fraction of the solute is doubled (from 0.2 to 0.4), the mole fraction of the solvent becomes 1 - 0.4 = 0.6.

Related NEET Chemistry questions

• At \( 80^{\circ} \mathrm{C}, \) the vapour pressure of pure liquid \( A \) is 520 mmHg and that of pure liquid \( B \) is 1000 mmHg. If a mixture solution of \( A \) and \( B \) boils at \( 80^{\circ} \) and 1 atm pressure, the amount of \( A \) (mole percent) in the mixture is:
• A solution is prepared by adding 2 g of substance \( A \) to 18 g of water. The mass percent of the solute is:
• Which of the following solutions shows positive deviation from Raoult's law?
• Which of the following forms an ideal solution? This question has multiple correct options
• Which of the following will show a negative deviation from Raoult's law?
• An aqueous solution of methanol in water has vapour pressure:

⚔️ Practice NEET Chemistry free + battle 1v1 →