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A liquid will fail to wet the surface of a solid when the angle of contact is

1. 0°
2. greater than 90°
3. less than 90°
4. 90°

Correct answer: greater than 90°

Solution

A liquid fails to wet a solid surface when the angle of contact exceeds 90°, indicating that the cohesive forces within the liquid are stronger than the adhesive forces between the liquid and the solid, leading to a tendency for the liquid to bead up rather than spread out.

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