A solution containing `1 mol` per litre of each `Cu(NO_(3))_(2), AgNO_(3),` and` Hg_(2)(NO_(3))_(2)` is being electrolyzed by using inert electrodes. The values of standard electrode potentials in volts `(` reduction potential `)` are
`Ag|Ag^(o+)=+0.80, 2Hg|Hg_(2)^(2+)=+0.79`
`Cu|Cu^(2+)=+0.34,Mg|Mg^(2+)=-2.37`.
With increasing voltage, the sequence of deposition of metals at the cathode will be

Options

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

Answer

A

Explanation

A cation havig highest reduction potential will be reduced first and so on. However, `Mg^(2+)` in aqueous
solution will not be reduced `(E_(Mg^(2+)//Mg)^(o)ltE_(H_(2)O//(1)/(2)H_(2)+OH^(-)))`
Instead water would be reduced in preference.