Among the following pairs of orbitals which orbital will experience the larger effective nuclearcharge? (i) 2s and 3s, (ii) 4d and 4f, (iii) 3d and 3p

The effective nuclear charge is the net positive charge experienced by an electron in a multi-electron atom. The greater the effective nuclear charge, the more strongly an electron is attracted to the nucleus.

(i) Between 2s and 3s, the 2s orbital will experience a larger effective nuclear charge. This is because the 2s orbital is closer to the nucleus and thus experiences a stronger attraction.

(ii) Between 4d and 4f, the 4d orbital will experience a larger effective nuclear charge. This is because the 4d orbital has a lower average distance to the nucleus compared to the 4f orbital.

(iii) Between 3d and 3p, the 3p orbital will experience a larger effective nuclear charge. This is because the 3p orbital is closer to the nucleus and thus experiences a stronger attraction.