Which substances have Delta. Hf = 0 kJ/mol by definition? Select all that apply. O2(g) N(g) H2O(l) Br2(l) Fe(s) He(g) S6(s).

it should be all of them because it asks if you included all of those in your answer

explanation:

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.

the answer is option a.