Explain the following observations: i) Water wets glass surface but does not wet the waxed glass surface.
ii) A steel needle placed carefully on the surface of water does not sink.
iii) A matchstick rubbed at one end with soap starts moving immediately in one direction when placed on the surface of water.
iv) The mass of a lump of goodies constant everywhre, but it'd weight is not.
v) Large mercury drops from oval balls on a glass slide