The energy of an electron in a hydrogenic ion depends on
Principal quantum number only
Principal and azimuthal quantum number only
Principal, azimuthal, magnetic quantum number only
All four quantum number
As we learn
Principal Quantum Number -
The principal quantum number determines the size and to a large extent the energy of the orbital.
The energy of hydrogenic ion depends on principal quantum number only
Hence, the option number (1) is correct.