2CO + O₂ -> 2CO₂

a. How many CO2 molecules are produced for every O2 molecule consumed?
b. How many CO2 molecules are produced for every CO molecule consumed?
c. How many moles of CO2 are produced when 2 moles of O2 were consumed?
d. How many moles of CO2 are produced when 5 moles of O2 are consumed?