Consider the reduction reaction Mn++ne−⟶M According to Faradays law, W=‌
M
n
×‌
i×t
F
=‌
M
n
×‌
Q
F
If W is the weight of substance deposited. Since W is given as 1g equivalent, which is equal to ‌
M
n
. Therefore, Q=F. 1F=96500 coulomb of charge = charge on 1 mole of electrons. Therefore, to deposit 1g equivalent of substance l mole of electrons is needed.