Wanda learned that deuterium (H-2); an isotope of hydrogen, has one proton and one neutron, and
that protium (H-1) has one proton and no neutrons.
She concluded that deuterium and protium are two
different elements.

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.