Question

Surface tension of a liquid does not depend on:
a.temperature
b.intermolecular force
c.surface area
d.solute dissolved in liquid

Answer 1

Sometimes we can see insects “walking” on the surface of water or when a leaf falls in a pond it keeps floating for some time. Have you ever wondered what causes such a phenomenon to happen?

Complete answer:
Before we start answering, let us know what are cohesive and adhesive forces.
Cohesive forces attractive forces between molecules of the same type.
Adhesive forces are attractive forces between molecules of different types.
Generally speaking, surface tension is a property of liquid surfaces which resists any force. In other words, it acts as a barrier for foreign materials to enter the liquid and holds the liquid together.
More scientifically, it is the attractive force acting downward on the surface molecules of a liquid by the molecules just beneath the surface layer. This force exerted by the tends to draw the surface molecules into the bulk of the liquid, making the liquid take the shape which has the least surface area. Now let’s see our options:
We know that, with increase in temperature, intermolecular forces decrease. Hence, surface tension also decreases.
Intermolecular forces vary from liquid to liquid, resulting in different surface tensions.
Cohesive forces are responsible for surface tension, not the surface area of the liquid. It is independent of the surface area of the liquid.
Dissolving any solute in the liquid will change the intermolecular forces, resulting in the change in surface tension.

Therefore, the correct option is (c).

Note:
Water has the largest surface tension of 72.7 N/m and as we increase the temperature, the surface tension decreases. At the boiling point i.e. 100 the surface tension of water is zero. Mercury is only the metal which is liquid at room temperature and its surface tension is 425.41 N/m.