A solution containing one mole per litre of each `Cu(NO_(3))_(2), AgNO_(3), Hg_(2)(NO_(3))_(2)` is being electrolysed by using inert electrodes. The values of standard electrode potentials in volts (reduction potentials) are
`Ag^(+)//Ag = +0.80 V, HG_(2)^(2+)//Hg = +0.79 V`
`Cu^(+)//Cu = +0.34 V, Mg^(2+)//Mg = -2.37 V`
With increasing valtage, the sequence of deposition of metals on the 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

A cation having highest reduction potntial will be reduced first and so on. However, `Mg^(2+)` in potential will be reuced first and so on . Howerver , `Mg^(2+)` in aqueous solution will not be reduced `(E _(Mg^(2+))^2//Mg^@ lt E_(H^2O.//1/2H_2 +OH^(-)))` Instead water would be reduced in prefernce .