At STP, which gaseous sample has the same number of molecules as 5.0 liters of O2 (g)?
A) 6.0 L of F2 (g)
C) 3.0 L of H2 (g)
B) 4.5 L of O2 (g)
D) 5.0 L of Cl2 (g)

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.