Question

With the addition of impurities, the surface tension of a liquid
A. Increases
B. Decreases
C. Remains constant
D. May increase or decrease depending on impurities.

Answer 1

Hint: This is a theoretical problem. The properties of the surface tension of the liquid and the properties of the impurities should be known to solve this problem. We know that the surface tension of the liquid gets affected upon the addition of impurities.

Complete answer:
The surface tension of the liquid gets affected by the type of impurities added to the liquid and the properties of the impurities. Some of the impurities will be highly soluble, some will be sparingly soluble and some will be non solvable.
The sparingly soluble substances reduce the surface tension of the liquid, whereas, the completely soluble substances increase the surface tension of the liquid. Even the temperature of the liquid plays an important role while finding the surface tension of the liquid. As the critical temperature, the surface tension of the liquid vanishes, whereas, the surface tension of the liquid becomes zero, at the boiling point of the liquid.
Here, we will be using the type of impurities property to solve this question. In this question, as the type of the impurities is not mentioned, so, the surface tension of a liquid may increase or decrease.
With the addition of impurities, the surface tension of a liquid may increase or decrease depending on impurities.

So, the correct answer is “Option D”.

Note: The properties of the surface tension of the liquid is the main concept of this question using which this can be solved. Even the types of impurities and their physical properties should be known. Even the temperature of the liquid plays an important role while finding the surface tension of the liquid.