Question

If 5.0 liters of carbon dioxide gas are produced by the reaction below at STP, how many liters of oxygen gas were used in the reaction?

2CO (g) + O2 (g) yields 2CO2 (g)

10.0 L
7.5 L
5.0 L
2.5 L

Answer 1

Answer: 2.5 L, use your dimensional analysis

Answer 2

V(O₂) : V(CO₂) = 1 : 2

x (O₂) : 5 L (CO₅)

x=5*1/2=2.5 L