[unleash10]

Here is the question:

If the time and current are each uncertain by 1 % and the mass of copper is uncertain be 0.1% what is the uncertainty in the calculated electron charge?

Q= I*t , what do i do with the uncertainty of the mass of copper?

[Borek]

IMHO you have to choose which of the two uncertanities should be used.

Hard to tell without knowing anything about the reaction conditions (unknown parameter being called current efficiency).