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Question:

15 eV is given to e⁻ in 4th orbit then find its final energy when it comes out of H⁻ atom.

12.08 eV

14.15 eV

13.6 eV

15.85eV

Solution:

Correct option is A. 14.15 eV
As we know that
Energy of nth orbit of H⁻ atom = -13.6/n²
Energy of 4th orbit of H⁻ atom = -13.6/16 = -0.85 eV
Hence Ionisation Energy of 4th orbit of H⁻ atom = 0.85 eV
So energy release = total energy - ionization energy of 4th orbit = 15 - 0.85 = 14.15 eV.