The potential associated with each electrode is known as electrode potential. If the concentration of each species taking part in the electrode reaction is unity (if any appears in the electrode reaction, it is confined to 1 atmospheric pressure) and further the reaction is carried out at 298 K, then the potential of each electrode is said to the standard electrode potential. By convention, the standard electrode potential of hydrogen electrode is 0.0 volt. The electrode potential value for each electrode process is a measure of relative tendency of the active species in the process to remain in the oxidised/reduced form. A negative `E^(@)` means that the redox couple is a stronger reducing agent than the `H^(+)//H_(2)` couple. A positive `E^(@)` means that the redox couple is a weaker reducing agent than the `H^(+)//H_(2)` couple. The metal with greater positive value of standard reduction potential forms the oxide of greater thermal stability.
Given the stadard reduction potentials,
`E_(K^(+)//K)^(@)=-2.93 V, E_(Ag^(+)//Ag)^(@)=+0.80 V, E_(Hg^(2+)//Hg)^(@)=0.79 V`
`E_(Mg^(2+)//Mg)^(@)=-2.37 V, E_(Cr^(3+)//Cr)^(@)=-0.74 V`.
The correct increasing order of reducing power is :

Options

A. `K gt Mg gt Cr gt Hg gt Ag`
B. `Ag gt Hg gt Cr gt Mg gt K`
C. `Mg gt K gt Cr gt Hg gt Ag`
D. `Cr gt Hg gt K gt Mg gt Ag`

Answer

A