In a 1.00 L container, 1 mole of SO₃ is decomposed. At equilibrium, 0.300 mole of O₂ is present. Calculate the concentrations of SO₂ and SO₃ at equilibrium, and calculate Keq.
2 SO₃ (g) ⭤ 1 SO₂ (g) + O₂ (g)