Which situation would cause the following equilibrium reaction to decrease the formation of products 2SO2 (g) + O2 (g) forward backward arrow 2SO43 (g) + energy

The reaction is as Follow,

2 SO₂ + O₂ ⇄ 2 SO₃ ΔH = - 94.58 kJ mol⁻¹

Changing Concentration:

According to Le Chatelier's principle, the removal of SO₂ and O₂ (or decrease in their concentration) at equilibrium will result in decrease in the formation of SO₃.

Changing Pressure:

As the reaction proceeds by the decrease in volume, so by decreasing the pressure will shift the equilibrium in backward direction decreasing the concentration of product.

Changing Pressure:

Since the forward reaction is exothermic, the equilibrium will be shifted in backward direction by increasing the temperature.