5 moles.
think about the ratio of moles of iron oxide (Fe2O3) and iron (Fe) in that balanced chemical equation, which is 1:2, respectively. if there are 10 moles of Fe, you would divide that by 2 to get the number of moles of Fe2O3.
16.94/18=.9411111
sig figs: 0.9411 mole of water
Volume well in the picture the fish tank seems to be a rectangle, so you would do V=length x width x height. So V=5x3x3=45