OnlineCBT
Chemistry · PYQ NEET UG 2025
हिन्दी5 moles of liquid X and 10 moles of liquid Y make a solution having a vapour pressure of 70 torr. The vapour pressures of pure X and Y are 63 torr and 78 torr respectively. Which of the following is true regarding the described solution?
Correct answer · Option 2
The solution shows negative deviation.
Explanation
Calculated \( P_{\text{total}} = P_X^0 x_X + P_Y^0 x_Y = 63 \times (5/15) + 78 \times (10/15) = 21 + 52 = 73 \text{ torr} \). Since observed \( P (70 \text{ torr}) < P_{\text{ideal}} (73 \text{ torr}) \), it shows negative deviation.
