Carbon monoxide (CO) contains carbon and oxygen in the mass ratio of 3 : 4. How much oxygen will combine with 9 g of carbon to form carbon monoxide? [Pg. No. 167]

Carbon monoxide (CO) contains carbon and oxygen in the mass ratio:

$$\text{Carbon} : \text{Oxygen} = 3 : 4$$

This means 3 g of carbon combines with 4 g of oxygen. So, we need to find how much oxygen will combine with 9 g of carbon.

If 3 g carbon combines with 4 g oxygen, then 9 g carbon will combine with:

$$\frac{4}{3} \times 9 = 12 \text{ g}$$

So, 12 g of oxygen will combine with 9 g of carbon to form carbon monoxide.