Explain the effect of (i) density
(ii) temperature and (iii) pressure on the viscosity of liquids and gases.

Explanation

(i) In case of liquid , viscosity increase with increase in density and for gases, it decreases with increase in density.
(ii) with the rise in temperature, the viscosity of liquid decrease while that of gases increases.
(iii) With ithe increases in pressure, the viscosity of liquids (expect water) increases while that of gases in practically independent of pressure. The viscosity of water decreases with the increase in pressure.