JEE Main · 2005 · 08 May 2005 · Offline · Atomic Structure

In a multi-electron atom the energy of an orbital is set by the principal and azimuthal quantum numbers together, $n$ and $l$, while the magnetic quantum number $m$ makes no difference unless an external field is applied. Scanning the list for a matching pair of $n$ and $l$, the orbitals with $n=3,l=2$ (the $3d$ set) appear twice, in (d) with $m=1$ and in (e) with $m=0$. Since they share the same $n$ and $l$ and differ only in $m$, those two have the same energy.