Question

Mercury does not wet glass, wood or iron because:

• A. Cohesive force is less than adhesive force.
• B. Cohesive force is greater than adhesive force.
• C. Angle of contact is less than ${90}^{\circ }$.
• D. Cohesive force is equal to adhesive force.

Answer 1

The correct option is B Cohesive force is greater than adhesive force.

For mercury, the cohesive force (between mercury molecules) is greater than adhesive force (between molecules of mercury and the solid material). Also, angle of contact with the surface is greater than ${90}^{\circ }$.

Hence, mercury will tend to repel when poured on the surface of wood, glass or iron. Therefore, no mercury particles are left behind on the surface of glass, wood or iron.