Physics · Bohr model, energy levels, hydrogen spectrum

An electron with energy 12.09 eV strikes hydrogen atom in ground state and gives

An electron with energy 12.09 eV strikes hydrogen atom in ground state and gives its all energy to the hydrogen atom. Therefore hydrogen atom is excited to

  • A. Fourth
  • B. Third
  • C. second
  • D. First

Step-by-step solution

The ground state energy of hydrogen is -13.6 eV. Energy absorbed to go from n=1 to n=n is ΔE = 13.6(1 - 1/n²) eV. Setting ΔE = 12.09 eV gives 1 - 1/n² = 12.09/13.6 ≈ 0.88897, so 1/n² ≈ 0.11103, n² ≈ 9.006, thus n=3. Hence the atom is excited to the third energy level.
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