i.CH4(g)⇌C(s)+2H2(g) △H1=+75.0kJ/mol
ii.CO2(g)+H2(g)⇌CO(g)+H2O(g) △H2=+41.0kJ/mol
iii.CO(g)+H2(g)⇌C(s)+H2O(g) △H3=-131.0kJ/mol