The quantum number which explains the line spectra observed as doublets in the case of hydrogen and alkali metals, and doublets and triplets in the case of alkaline earth metals is:

The two electrons occupying the same orbital are distinguished by:

Statement $1$: The energy of an electron is determined by the principal quantum number.
Statement $2$: The principal quantum number $(n)$ indicates the distance of the electron from the nucleus.

Although no currently known element contains electrons in $g$ orbitals in the ground state,it is possible that such an element will be found or that electrons in excited states of known elements could be in $g$ orbitals. For $g$ orbitals,$l = 4$. What is the lowest value of $n$ for which $g$ orbitals could exist? What are the possible values of $m_l$? How many electrons could a set of $g$ orbitals hold?

The number of nodal planes (planes of zero electron density) in the $d_{xy}$ orbital is:

For the energy levels in an atom,which one of the following statements is correct?