Question

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

Answer 1

Correct Answer - D
A cation having highest reduction potential will be reduced first and so on. However, ` Mg^(2+)` in aqueous solution will not be reduced
`(E_(Mg^(2+)//Mg)^(@) lt E_(H_2 O.//(1)/(2)H_2+OH^-))`. Instead wated would be reduced in prefence .