Question

Match the correct mole ratio to the substances in the reactions below.

carbon monoxide to iron in the reaction: Fe2O3 + CO ==> Fe + CO2

water to manganeese(II) chloride in the reaction: HCl + MnO2 ==> H2O + MnCl2 + Cl2

sodium to oxygen in the reaction: Na + O2 ==> Na2O

copper to iron in the reaction: Fe + CuSO4 ==> FeSO4 + Cu

Answer 1

First, you must balance the equation. (I assume you must balance the equation; it doesn't make sense to list mol ratios for equations that won't work.) Then you look at the coefficients of the material in the equation.
Fe2O3 + 3CO ==> 2Fe + 3CO2

Now, carbon monoxide, CO, is to iron, Fe, as 3/2.
The others are done the same way.