A solution that shows **positive** deviation from Raoult's law typically has:
A$\Delta_{mix}H < 0$ and $\Delta_{mix}V > 0$
B$\Delta_{mix}H = 0$ and $\Delta_{mix}V = 0$
C$\Delta_{mix}H < 0$ and $\Delta_{mix}V < 0$
D$\Delta_{mix}H > 0$ and $\Delta_{mix}V > 0$
Answer & Solution
Correct answer: D. $\Delta_{mix}H > 0$ and $\Delta_{mix}V > 0$
Positive deviation arises when solute–solvent interactions are weaker than like–like, so mixing absorbs heat ($\Delta H > 0$) and the molecules are held less tightly, expanding the volume slightly ($\Delta V > 0$). Negative deviation gives the opposite signs.
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