Question

Based on the given figure, the number of correct statement/s is/are _______

A. Surface tension is the outcome of equal attractive and repulsive forces acting on the liquid molecule in bulk
B. Surface tension is due to uneven forces acting on the molecules present on the surface
C. The molecule in the bulk can never come to the liquid surface
D. The molecules on the surface are responsible for vapour pressure if the system is a closed system

Answer 1

Correct Answer: 2

To determine the number of correct statements, let's analyze each option based on surface tension concepts:

1. A. Surface tension is the outcome of equal attractive and repulsive forces acting on the liquid molecule in bulk.
   This is incorrect. In the bulk, a molecule experiences equal forces from all directions, cancelling out, and thus does not contribute to surface tension.
2. B. Surface tension is due to uneven forces acting on the molecules present on the surface.
   This is correct. Molecules on the surface experience uneven forces because they are pulled more towards the bulk liquid than towards the air, creating surface tension.
3. C. The molecule in the bulk can never come to the liquid surface.
   This is incorrect. Molecules in the bulk can move to the surface due to thermal motion and diffusion.
4. D. The molecules on the surface are responsible for vapour pressure if the system is a closed system.
   This is correct. Surface molecules can escape the liquid to form vapor, contributing to vapor pressure in a closed system.

Correct statements: B and D, which is 2. This matches the expected range (2,2).