chemistry electrolyte and amount of substance related question

Question

A certain quantity of electricity is passed through aqueous solution of AgNO₃ and   CuSO₄ connected in the series . If Ag (at wgt. 108) deposited at the cathode is 1.08 g , then Cu deposited at the cathode is ?(at wgt. of Cu=63.53)

 

1. 3.177
2. 0.6354
3. 0.317
4. 6.354

Answer 1

3 is the correct answer:

 

Solutions are connected in series means the same charge passed. 1.08g of AgNO3 is 0.01 mol and reduction of Ag+ is one electron process. Since reduction of Cu++ is two electron process, two times less of Cu++ will be reduced with the same amount of charge. 0.01mol * 1/2 * 63.53 g/mol = 0.317 g