If you were given oxygen (molecular mass = 18 AMU) and hydrogen (molecular mass = 1 AMU) at the same temperature and pressure, which has more energy? Which gas would be moving faster? Why? How is this different than energy?

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride