CBSE Class 12-science Answered

(i) At cathode:

            The following reduction reactions compete to take place at the cathode.

 The reaction with a higher value of E⁰ takes place at the cathode. Therefore, deposition of silver will take place at the cathode.

            At anode:

 The Ag anode is attacked by  NO₃^-  ions. Therefore, the silver electrode at the anode dissolves in the solution to form Ag⁺.

            (ii) At cathode:

            The following reduction reactions compete to take place at the cathode.

The reaction with a higher value of E⁰ takes place at the cathode. Therefore, deposition of silver will take place at the cathode.

            At anode:

            Since Pt electrodes are inert, the anode is not attacked by NO₃^-   ions. Therefore, OH⁻ or   NO₃^- ions can be oxidized at the anode. But OH⁻ ions having a lower discharge potential and get preference and decompose to liberate O₂.

            (iii) At the cathode, the following reduction reaction occurs to produce H₂ gas.

            At the anode, the following processes are possible.

            For dilute sulphuric acid, reaction (i) is preferred to produce O₂ gas. But for  concentrated sulphuric acid, reaction (ii) occurs.

            (iv) At cathode:

            The following reduction reactions compete to take place at the cathode.

 The reaction with a higher value of E⁰ takes place at the cathode. Therefore, deposition of copper will take place at the cathode.

            At anode:

            The following oxidation reactions are possible at the anode.

 At the anode, the reaction with a lower value of E⁰ is preferred. But due to the overpotential of oxygen, Cl⁻ gets oxidized at the anode to produce Cl₂ gas.