Question

A liquid would wet the solid if adhesion forces as compared to cohesion forces are

• A. less
• B. more
• C. equal
• D. there is no such criteria

Answer 1

The correct option is B more

$Answer:-$ B

Pour some water into a glass container and the surface of the water will be level except where it contacts the glass. Where it contacts the glass it will be seen to rise above the water level for a short distance, clinging to the glass, as shown in Fig(a).. The water in this case is said to wet the surface of the container. Here the water molecules are more strongly attracted to the glass molecules than to themselves. That is, the force of adhesion between the water and glass molecules is greater than the force of cohesion between the water molecules.

Now pour some mercury into a glass container. The surface of the mercury will be level except where it contacts the glass, where the edges are depressed, dropping below the mercury level, as shown in Fig.(b). In this case the force of cohesion between mercury molecules is greater than the force of adhesion between them and the glass. If the force of cohesion is greater than the force of adhesion, the liquid will cling to itself and will tend to form droplets when placed on a smooth surface instead of spreading out to wet the surface.