I'm so sorry but I still don't understand, what do you mean by 'how many moles of electrons'? I didn't know electrons have a mole number?
Is it because 2e are needed for the oxidation of Zn and since there is .5 more mole of zinc metal than of the vanadium compound that the amount of electrons are 1? ...? O.ooo
The word 'mole' just refers to Avogadro's number, which is approximately 6.02 * 10
23. You can apply 'mole' to anything, not just atoms or molecules - the number of apples I have, the number of times I've failed at Chemistry etc. So if I have one mole of electrons, it just means that I have 6.02 * 10
23 electrons.
So if we have 1.5 mol of zinc, and each zinc atom gives off 2 electrons when it is oxidised to Zn
2+, we would have 1.5 * 2 = 3.0 mol of electrons.
Now we know that 3.0 mol of electrons are required to reduce 1 mol of the vanadium compound. That means the ratio between the electrons and the vanadium compound in the equation must be 3:1. Hence, the answer is equation b).