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

(N/A) Effective nuclear charge $(Z_{eff})$ is the net positive charge experienced by an electron in a multi-electron atom. The closer an orbital is to the nucleus,the greater is the $Z_{eff}$ experienced by the electron$(s)$ in it.
$(i)$ The $2s$ orbital is closer to the nucleus than the $3s$ orbital,so $2s$ experiences a greater $Z_{eff}$.
$(ii)$ The $4d$ orbital is closer to the nucleus than the $4f$ orbital,so $4d$ experiences a greater $Z_{eff}$.
$(iii)$ The $3p$ orbital is closer to the nucleus than the $3d$ orbital,so $3p$ experiences a greater $Z_{eff}$.