How many molecules are in .5 moles of h2

I am not sure if .5 is 5 or 0.5 but, one mole has 6.023 * 10^23 molecules, so 0.5 moles has 3.01 * 10^23, and 5 moles has 30.12 * 10^23 molecules

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.