Q12 / 201 · NTA Abhyas (NEET) 2020 · Physics · Atomic Physics

An H-atom in the ground state is excited by monochromatic radiation of photon energy 13.056 eV. The number of emission lines will be (given its ionisation energy is 13.6 eV)

  • A
    one
  • B
    two
  • C
    four
  • Correct answer
    D
    ten

Solution

If n, is the value of excited state, then

number of spectral lines = n n - 1 2

Energy of electron in ground state= – (ionisation energy) =-13.6 eV

Final energy -13.6+13.056=-0.544 eV

If n be the value of excited state, then

-13.6n2=-0.544

⇒         n2=25

⇒         n=5

Now, the number of spectral lines are

=nn-12=5×42=10 lines

Hence, the correct answer is option: 'D'.

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