In a hydrogen electrode a steady stream of hydrogen gas in passed over

Options

A. a piece of platinum with a rough surface immersed in a salt solution
B. a carbon immersed in an acidic solution
C. silver metal immersed in an acidic solution
D. a platinized platinum strip immersed ina n acidic solution

Answer

C

Explanation

The ion|insoluble salt | metal electrode consists of a metal `M` convered by a layer of insoluble salt `MX`, the whole immerseed in a solution containing the anion `X^(-)`. The electode is denoted as `MX|M|X^(-)`. A common example is the chloride/silver chloride/silver electrode. It is prepard by the electrolyzing a solution of `KCl` between a cathode and an `Ag` anode.
During the preparation of an `Ag-AgCl-Cl^(-)` electode by electrolytic method, silver metal is oxidized to silver ion which leads to a very rapid formation of `AgCl` on the surface of the silver.