Given the following equation (and assuming all gases are measured under the same conditions of
temperature and pressure), calculate the volume of CO2 produced and the total volume of all gases
remaining at the end:
2 CO(g) + O2(g) → 2 CO₂(g)

a) 40 cm³ of CO reacts with 20 cm³ of O₂
b) 20 cm³ of CO reacts with 20 cm³ of O₂