Water is depressed in a glass tube whose inner surface is cotated with paraffin wax. Why?

Explanation

Water is depressed in a glass tube whose inner surface is cotated with paraffin wax because of the fact that force of cohesion between molecules of water is larger than the force of adhesion between the moleculesa of water and wax. Therefore the water does not wet paraffin wax. The height upto which a liquid riese in a capillary tube is given by
`h= ( 2S cos theta)/(r rho g)`
Since water does not wet paraffin wax. `theta` is obutuse (i.e., `theta gt 90^(@))` , `cos theta` is negative. Hence h is -ve . therefore water is depressed in such a tube.