Q. Given the standard reduction potentials ${Zn}^{2 +}/Zn\ = \ - 0.74\ V,\ \ {Cl}_{2}\ /\ {Cl}^{-}\ = \ 1.36\ V$ $H^{+}/\frac{1}{2}H_{2}\ = \ 0\ V\ \ and\ \ \ \ Fe^{2 +}\ \ /\ {Fe}^{3 +} = \ 0.77\ V$ The order of increasing strength as reducing agent is
A) ${Cl}^{-},\ Zn\ ,\ H_{2},\ {Fe}^{2 +}$
B) $H_{2},\ Zn,\ {Fe}^{2 +},\ {Cl}^{-}$
C) ${Cl}^{-},\ {Fe}^{2 +},Zn\ ,\ H_{2}$
D) ${Cl}^{-},\ {Fe}^{2 +},\ H_{2}\ ,\ Zn$
Explanation
(d)
The substances which have lower reduction potentials are stronger reducing agents. Hence, the order of strength of reducing agent is increases in the following order
$\frac{{Cl}^{-} < \ {Fe}^{2 +} < \ H_{2} < \ Zn}{strength\ of\ reducing\ agent\ increases}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.