If an organism is heterozygous, it has one copy of two different alleles. If an organism is homozygous, it has two copies of the same allele.
First find the molar mass of Fe2O3, after you would want to do this
120 g Fe2O3 x 1 mol = # mol
Molar Mass
The answer is (3). The reaction that can occur at the anode is oxidation reaction which will lose electrons. So (1) and (2) are not correct. For (4) Fe3+ can not lose electrons again.