Which one among the following does not wet the walls of the glass vess

Which one among the following does not wet the walls of the glass vessel in which it is kept ?

Water

Alcohol

Mercury

Phenol

Answer is Right!

Answer is Wrong!

This question was previously asked in

UPSC NDA-1 – 2015

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Whether a liquid wets a solid surface depends on the balance between adhesive forces (attraction between liquid molecules and solid surface) and cohesive forces (attraction between liquid molecules). Water, alcohol, and phenol have adhesive forces with glass that are stronger than their internal cohesive forces, causing them to spread out and wet the glass surface. Mercury, on the other hand, has very strong cohesive forces (due to metallic bonding) that are much stronger than the adhesive forces between mercury and glass. Therefore, mercury minimizes its contact area with the glass, forming a convex meniscus and does not wet the glass.

Wetting is determined by the relative strengths of adhesive forces between the liquid and the solid and cohesive forces within the liquid.

A liquid wets a surface if the angle of contact between the liquid and the solid is less than 90 degrees. A liquid does not wet a surface if the angle of contact is greater than 90 degrees (as is the case with mercury on glass, where it is obtuse).

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