According to the Kinetic Molecular Theory, how can the speed of solvent molecules be slowed down?

• A. By adding more solute to the solvent
• B. By increasing the pressure on the solvent
• C. By increasing the volume of the solvent
• D. By decreasing the temperature of the solvent

Answer: (D)

Verified step by step guidance

1. Understand the Kinetic Molecular Theory: This theory explains the behavior of gases and can be applied to liquids. It states that the speed of molecules is related to their kinetic energy, which is dependent on temperature.
2. Recognize the relationship between temperature and molecular speed: According to the theory, as temperature increases, the kinetic energy and thus the speed of the molecules increase. Conversely, as temperature decreases, the kinetic energy and speed decrease.
3. Identify the effect of temperature on solvent molecules: Lowering the temperature of a solvent reduces the kinetic energy of its molecules, thereby slowing down their speed.
4. Consider the other options: Adding more solute, increasing pressure, or increasing volume do not directly affect the speed of solvent molecules in the same way temperature does.
5. Conclude that decreasing the temperature is the most direct method to slow down the speed of solvent molecules, as it reduces their kinetic energy according to the Kinetic Molecular Theory.