question_answer

The level of mercury in a capillary tube is lower than the level outside when the capillary is inserted in mercury. Explain.

Answer:

                This is explained in terms of cohesive and adhesive forces. The attractive forces in the molecules of the same substance are called cohesive forces while those in the molecules of different substances are called adhesive forces. In case of mercury, the cohesive forces are stronger than the adhesive forces. As a result, mercury gets detached from the glass surface and its level therefore, goes down in the capillary tube.