Explain how the energy of an orbital and the extent of shielding in the same shell depend on the shape of the orbitals.

(N/A) Both the attractive and repulsive interactions depend upon the shell and the shape of the orbital in which the electron is present. The reasons are as follows:
$(i)$ The $s$-orbital shields the outer electrons from the nucleus more effectively compared to electrons present in the $p$-orbital.
$(ii)$ Due to the spherical shape of the $s$-orbital,the $s$-orbital electron spends more time close to the nucleus in comparison to the $p$-orbital electron,which in turn spends more time near the nucleus compared to the $d$-orbital electron.
$(iii)$ Effective nuclear charge $(Z_{eff})$: As the azimuthal quantum number $(l)$ increases,the $Z_{eff}$ experienced by the electron decreases. Consequently,the $s$-orbital electron is more tightly bound to the nucleus than the $p$-orbital electron,which is more tightly bound than the $d$-orbital electron.
Result: The energy order of orbitals in the same shell is $s < p < d < f$.