If the binding energy of the electron in a hydrogen atom is 13 . 6   eV , the energy required to remove…

If the binding energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of Li++ is :
  1. 13.6 eV
  2. 3.4 eV
  3. 122.4 eV
  4. 30.6 eV

Solution

Energy of an electron in nth orbit of an ion with atomic number z is, E=-13.6×z2n2 eV

for 1st excited state of Li++, z=3, n=2

E=-13.6×32n2=-13.6×94 eV

     = -30.6 eV

∴  Required energy =30.6 eV

Asked in: JEE Main 2014 (09 Apr Online)

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