An aqueous solution containing one mole per litre each `Cu(NO_3)_2, AgNO_3, Hg(NO_3)_2, Mg(NO_3)_2` , being electrolysed using inert electrode. The values of standard electrode potential in volts are
`underset(Cu^(2+)|Cu=+0.34)(Ag^+|Ag=+0.80)` `underset(Mg^(2+)|Mg=-2.37)(Hg^+|2Hg=+0.79`)
With increasing voltage, the sequence of deposition of metal on cathode will be

Options

A. Ag, Hg, Cu, Mg
B. Mg, Cu, Hg, Ag
C. Ag, Hg, Cu
D. Cu, Hg, Ag

Answer

C

Explanation

Higher the reduction potential, more easily is the metal deposited. `H_2O` is reduced more easily than `Mg^(2+)` ions, hence `Mg^(2+)` ions will not be deposited.