Question

The quantum number which determines the energy of a sublevel is:
(A) $ n $
(B) $ l $
(C) both A and B
(D) neither A nor B

Answer 1

Hint :In order to this question, to know the correct option for the given statement or to know the factors on which the energy of a sublevel is dependent, we will go through the concept of energy of orbitals in which we will explain the both quantum numbers.

Complete Step By Step Answer:
Energy depends on both principal and azimuthal quantum numbers.
And, here in the option, the principal quantum number is denoted by $ n $ and the azimuthal quantum number is denoted by $ l $ .
 $ greater\,n + l \Rightarrow greater\,energy $
The energy of orbitals refers to the energy required to take an electron present in that orbital to infinity or the energy released when an electron from an infinity is added to that orbital.
This orbital energy is determined by the quantum number $ (n) $ and the azimuthal quantum number $ (l) $ , both of which are determined by the shell and subshells. It is the same for all orbitals that belong to the same subshell, and degenerate orbitals are defined as orbitals with the same energy.
The energies of hydrogen and hydrogen-like particle orbitals are only determined by the value of the principal quantum $ (n) $ number, but the energies of multi-electron atoms are determined by both the main quantum number $ (n) $ and the azimuthal quantum number $ (l) $ . The energy is determined by the $ (n + l) $ value. Repulsion between electrons in a multi-electron atom is caused by the difference in energy of distinct subshells inside the same shell. The stability of a multi-electron atom is thus affected by toral attractive and repulsive interactions.
Hence, the correct option is (C) both A and B .

Note :
The primary distinction between azimuthal and principal quantum numbers is that the former describes the rotational momentum of an electron in an atom, while the latter describes the size of an electron orbital. The primary quantum number is denoted by $ n $ and the azimuthal quantum number is denoted by $ l $ .