CO (g) refers to carbon monoxide gas, which is a colorless and odorless gas composed of one carbon atom bonded to one oxygen atom.
Hydrogen gas, a diatomic molecule consisting of two hydrogen atoms bonded together.
Methanol gas, a simple alcohol compound composed of one carbon atom, four hydrogen atoms, and one oxygen atom.
The equilibrium constant for the reaction, which indicates the ratio of products to reactants at equilibrium.