Multiple choice

The first excited state of hydrogen atom is 10.2 e V above the ground state. What temperature is needed to excite hydrogen atoms to first excited level?

  1. 7.88 x 104 K

  2. 3.94 x 104 K

  3. 5.91 x 104 K

  4. 23.65 x 104 K

  5. 17.73 x 104 K
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A Correct answer
Explanation

Where K = 1.38 x 10-23 J/mole. 0K K.E. per atom = (3/2) KT K.E. of the hydrogen atom = 10.2 eV ∴ 10.2 eV = 10.2 x (1.6 x 10-19) joule T = (2/3) x ( K.E. per atom/ K)   = (2/3) x 10.2 x (1.6 x 10-19)/1.38 x 10-23  = 7.88  x 104 K

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