48) Which is the process of applying adhering layers of nobler metals to another metal's surface by dipping in a nobler metal solutin ion to produce a replacement reaction

49) Which is an example of sacrificial coating

50) 7.5% of 4000 is

51) Which one of the point given below lies in the 3rd quadrant of a Cartesian plane?

52) The number of atoms in the molecules of an element is called its