C18: Three gases, H₂, Kr and CH₄, are initially at the same p,V,T conditions. At constant volume the same amount of heat is added to the three gases. Order the gases according to their final temperature, starting with the hottest.

1) H₂ – Kr – CH₄

2) H₂ – CH₄ – Kr

3) CH₄ – Kr – H₂

4) CH₄ – H₂ – Kr

5) Kr – H₂ – CH₄