The standard electrode potentials $$\left( {E_{{M^ + }/M}^ \circ } \right)$$ of four metals $$A, B, C$$ and $$D$$ are $$ - 1.2\,V,0.6\,V,0.85\,V$$ and $$ - 0.76\,V,$$ respectively. The sequence of deposition of metals on applying potential is :
A.
$$A,C,B,D$$
B.
$$B,D,C,A$$
C.
$$C,B,D,A$$
D.
$$D,A,B,C$$
Answer :
$$C,B,D,A$$
Solution :
As the value of reduction potential decreases the reducing power increases i.e.
$$\mathop C\limits_{\left( {0.85} \right).} < \mathop B\limits_{\left( {0.6} \right).} < \mathop D\limits_{\left( { - 0.76} \right)} < \mathop A\limits_{\left( { - 1.2} \right)} $$
Releted MCQ Question on Physical Chemistry >> Electrochemistry
Releted Question 1
The standard reduction potentials at $$298 K$$ for the following half reactions are given against each
$$\eqalign{
& Z{n^{2 + }}\left( {aq} \right) + 2e \rightleftharpoons Zn\left( s \right)\,\,\,\,\,\,\,\,\, - 0.762 \cr
& C{r^{3 + }}\left( {aq} \right) + 2e \rightleftharpoons Cr\left( s \right)\,\,\,\,\,\,\,\,\, - 0.740 \cr
& 2{H^ + }\left( {aq} \right) + 2e \rightleftharpoons {H_2}\left( g \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,0.000 \cr
& F{e^{3 + }}\left( {aq} \right) + 2e \rightleftharpoons F{e^{2 + }}\left( {aq} \right)\,\,\,\,\,\,\,\,0.770 \cr} $$
which is the strongest reducing agent ?
A solution containing one mole per litre of each $$Cu{\left( {N{O_3}} \right)_2};AgN{O_3};H{g_2}{\left( {N{O_3}} \right)_2};$$ is being electrolysed by using inert electrodes. The values of standard electrode potentials in volts (reduction potentials) are :
$$\eqalign{
& Ag/A{g^ + } = + 0.80,\,\,2Hg/H{g_2}^{ + + } = + 0.79 \cr
& Cu/C{u^{ + + }} = + 0.34,\,Mg/M{g^{ + + }} = - 2.37 \cr} $$
With increasing voltage, the sequence of deposition of metals on the cathode will be :