With an increase in temperature, the viscosity of:
(a)
gases decrease.
(b)
liquids increase.
(c)
gases increase.
(d)
liquids decrease.
Which of the following options is/are correct?
1.
(b), (c)
2.
(a), (d)
3.
(c), (d)
4.
(a), (b)
Hint: The viscosity of a liquid depends on the intermolecular forces and the viscosity of the gases depends on the movement of the molecules.
Step 1: Find the variation of viscosity of the liquids with temperature.
For liquids, the coefficient of viscosity, \(\eta_{\text {liquid }} \propto \frac{1}{\sqrt{T}}\)
i.e. with an increase in temperature, \(\eta_{\text {liquid }}\)decreases.
Step 2: Find the variation of viscosity of the gases with temperature.
For gases, the coefficient of viscosity, \(\eta_{\text {gases }} \propto \sqrt{T}\)
i.e. with an increase in temperature, \(\eta_{\text {gases }}\) increases.
Hence, option (3) is the correct answer.
