One Faraday of electricity will liberate 1 gram atom of the metal from the solution of

${\mathrm{Cu}}^{2+} +\hspace{0.17em}2{\mathrm{e}}^{-}\to \mathrm{Cu}$ 

To deposit 1 g atom of Cu,  2F of electricity is required.

${\mathrm{Au}}^{3+}+3{\mathrm{e}}^{-}\to \mathrm{Au}$

To deposit 1 g atom of Au, 3F of electricity is required. 

${\mathrm{Ag}}^{+}+ 1{\mathrm{e}}^{-}\to \mathrm{Ag}$

To deposit 1g atom of Ag, 1F of electricity is required.