The four flasks below were prepared with the same volume and temperature. Flask I contains He atoms, Flask II contains Cl₂ molecules, Flask III contains Ar atoms, and Flask IV contains NH₃ molecules. Which flask has

(a) The largest number of atoms;

(b) The highest pressure;

(c) The greatest (mass) density;

(d) Molecules or atoms with the highest root mean square speed;

(e) Molecules or atoms with the highest molar kinetic energy?

II III IV