A $$5A$$  current is passed through a solution of zinc sulphate for $$40$$ $$min.$$  The amount of $$zinc$$  deposited at the cathode is

Solution :
$$\eqalign{ & {\text{Current,}}\,I = 5\,A \cr & {\text{time, }}t = 40\min = 40 \times 60{\text{ = }}2400{\text{ }}s \cr & {\text{Amount of electricity passed}} \cr & Q = It \cr & Q = 5 \times 2400 \cr & Q = 12000\,C. \cr & Z{n^{2 + }} + 2{e^ - } \to Zn \cr & n = 2{e^ - } \cr & {\text{From Faraday first law}} \cr & W = Z\,I\,t \cr} $$
   $$Z = {\text{equivalent mass}}$$     $$\left[ {65.39 = {\text{mass of zinc}}} \right]$$
$$\eqalign{ & \,\,\,\,\,\,\, = \frac{{Mass}}{{{e^ - } \times F}} \cr & \,\,\,\,\,\,\, = \frac{{65.39}}{{2 \times 96500}}\,g\,\,{\text{of }}zinc \cr & {\text{therefore, }}12000{\text{ }}C{\text{ charge will deposite}} \cr & {\text{ = }}\frac{{65.39 \times 12000}}{{2 \times 96500}} \cr & = 4.065\,g\,\,{\text{of }}zinc. \cr} $$