Answer: CO is considered as a product.
Step-by-step explanation:
A general chemical equation for a combination reaction follows:

To write a chemical equation, we must follow some of the rules:
- The reactants must be written on the left side of the direction arrow.
- A '+' sign is written between the reactants, when more than one reactants are present.
- An arrow is added after all the reactants are written in the direction where reaction is taking place. Here, the reaction is taking place in forward direction.
- The products must be written on the right side of the direction arrow.
- A '+' sign is written between the products, when more than one products are present.
For the given chemical equation:

are the reactants in the reaction and
are the products in the reaction.
Hence, CO is considered as a product.