Faraday's laws in code

You will write functions for the calculations of electrolysis. One finds the moles of electrons, one the mass deposited and one the time needed. The checker tests them with new numbers.

The idea. $Q = It$, the moles of electrons are $Q/F$, and the mass is $\dfrac{Q}{zF}M$. When the time is the unknown, $t = \dfrac{mzF}{MI}$.

Your tasks.

1. Complete moles_of_electrons(current, seconds) so that it returns the moles of electrons.
2. Complete mass_deposited(molar_mass, z, current, seconds) so that it returns the mass in grams.
3. Complete time_needed(molar_mass, z, current, grams) so that it returns the time in seconds.
4. Complete current_efficiency(actual, expected) so that it returns the percentage.