Question

Not considering the electron spin, the degeneracy of the second excited state is 9, while the degeneracy of the first excited state of the H atom is:

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is B

2

Degeneracy

• The degenerate orbitals are those orbitals that have the same energy levels.

Ground state and Excited states

• The ground state is the orbital in which electrons are present in their original energy levels.
• The excited state of an atom is that state in which electrons after absorbing energy jump to higher energy levels.

Excited state in H atom

• A hydrogen atom has only one electron in its 1s orbital.
• After absorbing energy the electron jumps from 1s to either 2s or the 3 2p orbitals (as all these p orbitals are degenerate).
• So, during the first excitation, the electrons from the 1s orbital will jump to 2s or either of the 3 2p orbitals.
• Therefore, the degeneracy of the first excited state of the H atom is 2.