At the same temperature, how does the internal energy of 1 mole of helium gas compare with the internal energy of 1 mole of argon gas? (Select all that apply.)
They are the same, partly because the average speed of the argon atoms and of the helium atoms are equal. Although the helium atoms have a smaller mass m, they move faster, and have more internal energy because 1/2mv2 depends linearly on the mass but quadratically on the speed. The helium has more internal energy, partly because the average speed of its atoms is greater. They are the same, partly because both have the same average kinetic energy per atom. They are the same, partly because both contain the same number of atoms. The argon has more internal energy, partly because its atomic mass and therefore its average kinetic energy is greater.