İ heard that : Charge of a mole of electrons/charge of single electron =avagadros constant How is this derived ?
The key is to determine the charge of a mole of electrons vs the charge of one electron.
We get the charge of one electron from the Milliken oil drop experiment.
For a mole of electrons you can start uf you firzt get the molar mass of water, call this $18.016$ grams per mole. Now electrolyze water with an inert electrolyte such as sodium sulfate. Work out the charge transfer required to decompose one mole = $18.016$ grams. This is two moles of electrons based on the stoichiometry of the electrochemical reaction. Half of this divided by the single electron charge is Avogadro's number.