50cm of carbon (II) oxide exploded with 150cm3 3 of air containing 20% oxygen by volume. Which of the reactants was in excess?

50cm of carbon (II) oxide exploded with 150cm${}^3$ of air containing 20% oxygen by volume. Which of the reactants was in excess?

Answer Details

2CO + O${}_2$ $\to$ 2CO${}_2$
50cm${}^3$ $\to$ 25cm${}^3$
20% $\times$ 150cm${}^3$
30cm${}^3$ is the volume of oxygen available for the reactions.
But only 25cm${}^3$ is required, therefore O${}_2$ is in excess.