How does the surface tension of a liquid vary with an increase in temperature?
(a) Remains same (b) Decreases
(c) Increases (d) No regular pattern is followed
Answer: (b) Decreases
The surface tension of liquids generally decreases with the increase of temperature and becomes zero at the critical temperature. The decrease in surface tension with increase of temperature is obviously doe to the fact with increase of temperature, the kinetic energy of the molecules increases and therefore, the intermolecular attraction decreases.
Note Surface tension of a liquid is defined as the force acting at right angles to the surface along one centimeter length of the surface. Units of surface tension are dyne per cm (or newtons per meter i.e., Nm−1 in the SI systems.)