There are three reactions with reaction enthalpy change (ΔH) values as follows:
S (s) + O₂ (g) → SO₂ (g); ΔH₁ = -296.8 kJ/mol
S (s) + 3/2 O₂ (g) → SO₃ (g); ΔH₂ = -395.6 kJ/mol
SO₃ (g) → SO₂ (g) + 1/2 O₂ (g); ΔH₃ = ?

According to Hess’s law, what is the calculated ΔH₃ for reaction 3 above?
(a) ΔH₃ = 98.8 kJ/mol
(b) ΔH₃ = -98.8 kJ/mol
(c) ΔH₃ = -296.8 kJ/mol
(d) ΔH₃ = 692.4 kJ/mol