Final answer:
At the same temperature, helium atoms have a higher average speed than neon atoms due to helium's lower molar mass, despite both gases having the same average kinetic energy.
Step-by-step explanation:
If the molar mass of helium is 4.0 g/mol and the molar mass of neon is 20.2 g/mol, the question asks about the relative average speeds of helium and neon atoms. According to the kinetic molecular theory, the average kinetic energy of gas particles is directly proportional to the temperature and does not depend on their mass. Hence, at the same temperature, helium and neon gases would have the same average kinetic energy. However, since the molar mass of helium is smaller, it will have a higher average speed compared to neon atoms at the same temperature.
The correct answer to the question is therefore (c) The average speed of the helium atoms is greater than the average speed of the neon atoms.