Question
5 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?
NEET
Chemistry
Solutions
2025
NEET 2025
NEET Chemistry Question (2025) — Solution
Options
- A. The solution shows positive deviation.
- B. The solution shows negative deviation.
- C. The solution is ideal.
- D. The solution has volume greater than the sum of individual volumes.
Answer
B. The solution shows negative deviation.
Step-by-step solution
array cc X & Y \\ n_x=5 & n_y=10 \\ P_x^0=63 & P_y^0=78 array aligned & aligned & P_ s( calc.) =P_x^0 x_x+P_y^0 X_y \\ & = 63 5 15 +78 10 15 \\ & =21+52 \\ & =73 \\ & P_ s (obs.) =70 \\ & P_ s (obs.) P_ s (calc.) aligned \\ & -ve deviation aligned
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