2CO(g) + O₂(g) → 2CO₂(g)
Explanation:
What is a  balanced chemical equation?
A balanced chemical equation is one that has equal number of atoms of each element involved in the reaction on both side of the equation.
How do we balance chemical equations?
Balancing chemical equations is a try and error process that involves putting appropriate coefficients on the reactants and products in a chemical reaction.
Why is it important to balance chemical equation?
Chemical equations are balanced so as to obey the law of conservation of mass.
In this case; the balanced chemical equation for the reaction between carbon monoxide and oxygen gas is given by;
2CO(g) + O₂(g) → 2CO₂(g)
This is because there are 2 carbon atoms and 4 oxygen atoms on both the reactant and product side.