To which one of these reactions occurring at 25°C does the symbol AHf [H2SO4(1)] refer?
2H(g) + S(g) + 40(g)--> H2SO4(1)
H2(g) + S(s) +202(g) --> H2SO4(1)
H2SO4(1) --> H2(g) + S(s) +202(g)
H2SO4(1) --> 2H(g) + S(s) +40(g)
