If I am not mistaken,
(Number of moles)=(mass)/(molar mass)
So, (mass)=(Number of moles)*(molar mass)
Moreover, we uses mole ratio directly from the balanced equation. Take question 2 as an example, you have 300000 mol of Fe2O3. From the balanced equation, mole ratio of Fe2O3 and Fe is 1:2, i.e. 1 mol of Fe2O3 gives 2 mol of Fe. Thus, 300000 mol of Fe2O3 gives 600000 mol of Fe. Then, you have to multiply that 600000 mol of Fe with its molar mass, which is 56. Finally, you get 600000*56=33600000g of Fe, or 33.6 tonnes of Fe.
Please kindly correct me if I have made any mistakes.