Question

Which of the following is correct regarding the variation of a liquid's viscosity with temperature?
1. Viscosity decreases with the increase in temperature of a liquid
2. Viscosity increases with the increase in temperature of a liquid
3. Viscosity decreases first and then increases when temperature of a liquid is increased
4. Viscosity remains unchanged

Answer 1

Correct Answer - Option 1 : Viscosity decreases with the increase in temperature of a liquid

The correct answer is option 1) i.e. Viscosity decreases with the increase in temperature of a liquid

CONCEPT:

• Viscosity: The viscosity is the resistance offered to the flow of fluids.
  • At the molecular level of fluids, it is the internal friction between molecules of the fluids.
  • A fluid with low viscosity will easily flow as the internal friction is less.

EXPLANATION:

• On increasing the temperature of the liquid, the kinetic energy increases, and the molecules become more mobile.
• Thus, the molecules can now easily overcome the intermolecular forces binding them together. 
• Thus, the binding energy of molecules is reduced, and therefore, the viscosity is reduced.