Mole ratio of 2S02 + O2 ≥ 2SO3

Answer 1

The mole ratio is the ratio of coefficients in the chemical equation.

2 SO₂ + O₂ --> 2 SO₃

Since there is no coefficient in front of O2, we assume that it is one (1).

These are the coefficients for each reactant and product:

2: SO2

1: O2

2: SO3

The mole ratio is all of these coefficients put together:

2:1:2

Meaning, for every 2 molecules of SO2, there is 1 molecule of O2 and 2 molecules of SO3.