62) For silver plating of all the external surfaces of a solid cylinder with 5 cm diameter and 12 cm length, the total current required is _____, if the current density applied is 2.5 Amp/dm2.

63) Zincating is required for electroplating on

64) _____ of light is responsible for producing rainbows.

65) Woods Nickel plating is employed as undercoat to plate on

66) Valency of Copper in Copper sulphate is