Suppose the carbon and oxygen react according to the equation: o2 + 2c = 2co. if you started with sixty oxygen molecules (60o2) and sixty carbon (60c), how many carbon monoxide molecules could you make?

O2 + 2C=2CO

from equation for 1 molecule O2 is needed 2 molecules C, and we get 2 molecules of CO

ratio O2:2C=1:2

so for 60 atoms of carbon we need only 30 molecules of oxygen.

and from 60 atoms of carbon we get 60 molecules of CO, because from 2 atoms of C we get 2 molecules of CO