Nuclear charge is defined as the net positive charge experienced by an electron in the orbital of an atom exerted by the nucleus of the atom. The closer the orbital, the greater is the nuclear charge experienced by the electron [s] in it and the nuclear charge is inversely proportional to the distance of the electron from the nucleus.

(i) 3s is farther away from the nucleus as compared to 2s. Hence 2s will experience larger effective nuclear charge as compared to 3s.

(ii) In this case 4d will experience more nuclear charge as compared to 4f as 4d is more near to the nucleus.

(iii) 3f is farther away from the nucleus as compared to 3p. Hence 3p will experience larger effective nuclear charge as compared to 3f.