Q6 / 60 · JEE Advanced 2015 (Paper 1) · Chemistry

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- is :

Correct answer: 3

Solution

Energy order of orbitals of H is decided by only principle quantum number (n) while energy order of H- is decided by (n+l) rule:
Electronic configuration of ′H-′ is -1s2 its energy order is decided by n+l rule.
H-=1s22s02p0
Its 2nd  excited state is 2p
And degeneracy 2p is 3.

Hence, the correct answer is 3.

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