The reaction
`1//2H2(g)+AgCl(s) rarr H^(o+)(aq)+Cl^(c-)(aq)+Ag(s) ` occurs in the galvanic cell.

Options

A. `Pt|H_(2)(g)|KCl(aq.)|AgCl(s)|Ag(s)`
B. `Pt|H_(2)(g)|HCl(aq.)|AgCl(s)|Ag(s)`
C. `Pt|H_(2)(g)|HCl(aq.)|AgNO_(30)(aq.)|Ag(s)`
D. `Ag|AgCl(s)|KCl(aq.)|AgNO_(30)(aq.)|Ag`

Answer

D

Explanation

The standard hydrogen electrode consists of a plati-num electrode coated with platinum black (i.e. finely divided platinum). The electrode is dipped in an acidic solution and pure hydrogen gas is bubbled through it. The concentration of both the reduced and oxidized forms of hydrogen is main-tained at unity. This imlpies that the pressure of hudrogen fas is one bar and the concentration of hydrogen ions in the solution is one molar.
Gas electrodes ultilize the phenomenon of adsorption of gas molecular by inert metals. The platinum electrode is pre-pareed by electrochemically depositing platicnum on platinum metal, which gives a large surface area for the adorption of gases.