Multiple choice

At what temperature does the average translational kinetic energy of a molecule in a gas equal to the kinetic energy of an electron accelerated from rest through a potential difference of 5 volt?

  1. 38.65 x 10<sup style="font-family:">3 K

  2. 8.69 x 10<sup style="font-family:">4 K

  3. 1.93 x 10<sup style="font-family:">4 K

  4. 2.89 x 10<sup style="font-family:">4 K

  5. 11.59 x 10<sup style="font-family:">4 K
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A Correct answer
Explanation

 K.E. of the electron is 5 eV = 5 x 1.6 x 10-19 J But K.E. = (3/2)KT ∴ 5 x 1.6 x 10-19 = (3/2)(1.38 x 10-23) x T T =  2 x 5 x 1.6 x 10-19/3 x 1.38 x 10-23   = 38.65  x 103 K

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