Question

3 molecules of oxygen (O2) react with 6 molecules of carbon monoxide (CO) to produce some amount of carbon dioxide (CO2)​

Answer 1

6 molecules of CO2

Step-by-step explanation:

3 (O2) + 6 (CO) ----> ? (CO2)

There's 12 oxygens, and 6 carbons in the reactant. You can put 6 as the coefficient of the product to get the same amount on the left as the right.