1. The problem statement, all variables and given/known data What is the average kinetic energy of an atom of helium gas at a temperature of 20 degrees C? 2. Relevant equations N/A 3. The attempt at a solution Here's my attempt at a solution: Using the equation E = kT/2 for each degree of freedom, I found that KE = 3kT/2 since an atom of He has three degrees of freedom in translational KE. Using this logic I fould that KE = 6.1 x 10^-21 while the correct answer should be 4.0 x 10^-21. Can someone help me understand where my logic/reasoning is incorrect? Thanks.