Question

How many moles of carbon monoxide are needed to react completely with 108 kg of Fe2O3. Fe2O3(s)+CO(g)→Fe(s)+CO2(g)

Answer 1

well, how many moles of Fe2O3 in 108kg?

Now balance the equation:

Fe2O3 + 3CO -> 2Fe + 3CO2

Now you can see how much CO is used.