Question

With the rise of temperature, the surface tension of a liquid ________.
A. increases
B. decreases
C. remains unchanged
D. None of the above

Answer 1

Hint: Surface tension of a liquid occurs due to attraction between the molecules which are on the surface of the liquid. When the temperature of the liquid increases then due to the kinetic energy of the molecules also increases.

Complete step by step solution:
In a liquid if we increase the temperature it further increases the velocity of all molecules and thus those molecules are not able to interact with other molecules very easily. As a result, their surface tension will decrease. When the temperature rises then the molecules get more kinetic energy which increases the velocity of molecules, it will weaken the intermolecular forces of attraction in liquid molecules and thus the surface tension of a liquid will decrease.

Hence option B is the correct answer.

Additional information: Surface tension is defined as the phenomenon when the surface of a liquid is in contact with another phase like liquid. Liquids have a tendency to acquire the least possible surface area. On the other hand, we can say that surface tension is the tension in the surface film of a liquid which is caused by the attraction of the particles present at the surface layer by the bulk of the liquid which results in minimisation in the surface area.

Note: Surface tension depends upon the forces of attraction between all the particles within the liquid and also it depends on the forces of attraction of solid, liquid or gas which are in contact with it.