Explain why
(a). The angle of contact of mercury with galss is obtuse, while that of water with glass is acute.
(b). Water on a clean glass surface tends to spread out while mercury on the same surface tends to form drops. (Put differently, water wets glass while mercury does not).
(c). Surface tension of a liquid is independent of the area of the surface
(d). Water with detergent disolved in it should have small angles of contact.
(e). A drop of liquid under no external forces is always spherical in shape.