Which of these factors does not govern the stability of a conformation in acyclic compounds?

The pH of a 0.02 M NH₄Cl solution will be :
[given K_b (NH₄OH) = 10^–5 and log 2 = 0.301]

For the reaction,
2SO₂(g) + O₂(g) = 2SO₃(g), $$\Delta $$H = –57.2 kJ mol^–1 and K_C = 1.7 × 10¹⁶
Which of the following statement is incorrect ?

The minimum amount of O₂(g) consumed per gram of reactant is for the reaction :
(Given atomic mass : Fe = 56, O = 16, Mg = 24, P = 31, C = 12, H = 1)