Properties Of Liquids

• Option 1: Correct. Viscosity decreases with an increase in temperature because the intermolecular forces are weakened, allowing liquid molecules to flow more easily.
• Option 2: Correct. Surface tension decreases with temperature due to reduced cohesive forces at the liquid surface.
• Option 3: Incorrect. Impurities increase viscosity by disrupting the liquid’s intermolecular interactions, making it harder for molecules to flow.
• Option 4: Correct. The effect of impurities on surface tension depends on the type of impurity. Impurities can either increase or decrease surface tension. For example, surfactants lower surface tension, while some other impurities might increase it.

Therefore, option 3 is incorrect.