Question

The angle of contact at the interface of water glass is 0°, ethyl alcohol-glass is 0°, mercury-glass is 140° and methyl iodide-glass is 30°. A glass capillary is put in a trough containing one of these four liquids. It is observed that the meniscus is convex. The liquid in trough is ____________.

Options

• water

• ethyl alcohol

• mercury

• methyl iodide

Answer 1

The angle of contact at the interface of water glass is 0°, ethyl alcohol-glass is 0°, mercury-glass is 140° and methyl iodide-glass is 30°. A glass capillary is put in a trough containing one of these four liquids. It is observed that the meniscus is convex. The liquid in trough is mercury.

Explanation:

Only when the angle of contact is obtuse is a convex meniscus conceivable. Only the mercury-glass pair meets this requirement among the offered liquids.