JEE Advanced · 2015 · 24 May 2015 · Paper 1 · Atomic Structure

Not considering the electronic spin, the degeneracy of the second excited state

(n = 3)

of H atom is 9, while the degeneracy of the second excited state of

H^{-}

Answer: 3

Solution

For H atom, energy depends only on n, so the second excited state (n=3) has orbitals 3s, 3p, 3d with degeneracy 1+3+5 = 9.

For

H^{-}

(configuration 1s²), energy follows (n+ℓ) rule. The ground state is 1s², first excited state is 2s, second excited state is 2p.

Degeneracy of 2p = 3.

JEE Advanced · 2015 · 24 May 2015 · Paper 1 · Integer answer

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