Ethanol + water shows positive deviation. Explain at molecular level. Step 1: Pure water: strong H-bonds; pure ethanol: H-bonds. Step 2: Mixed: water–ethanol H-bonds are WEAKER than water–water (ethanol's bulky C₂H₅ disrupts the network). Step 3: Molecules escape more easily → vapour pressure HIGHER than Raoult predicts. Step 4: Extreme case: minimum-boiling azeotrope at 95.6% ethanol — distils unchanged, so absolute alcohol needs chemical drying, not distillation.