Question

How will a rise in temperature affect the viscosity of liquids and gases?

• A. Both increases
• B. Both decreases
• C. In case of liquids, decreases and in case of gases, increases.
• D. In case of liquid, increases and in case of gases, decreases.

Hint:

In general, viscosity decreases with an increase in temperature: - For liquids, this happens due to reduced intermolecular forces as the temperature rises. - For gases, higher temperatures lead to increased molecular motion, which reduces viscosity.

Answer 1

The Correct Option is B

Viscosity is a measure of a fluid's resistance to flow. The effect of temperature on viscosity is different for liquids and gases: 1. Liquids: As the temperature increases, the kinetic energy of the molecules in the liquid increases. This leads to a decrease in the intermolecular forces and thus a reduction in viscosity. Therefore, the viscosity of liquids decreases with an increase in temperature. 2. Gases: In gases, increasing the temperature causes the molecules to move more rapidly, which increases the frequency of collisions between them. This leads to a reduction in the effect of intermolecular forces, and the viscosity of gases also decreases with an increase in temperature. 
Thus, the correct answer is $\boxed{{B}}$, as the viscosity decreases in both liquids and gases with an increase in temperature.