Question: how to find moles of electrons?
Answer: The stoichiometric equation gives you the ratio of moles. If two electrons are lost by one species with a coefficient of 1 then the number of moles of electrons is 2 x 1. If you have 0.1 moles of zinc then 0.1 x 2 moles of electrons are lost. The stoichiometric equation gives you the ratio of moles.