Question

A standard reduction electrode potentials of four metals are
A = -0.250 V, B = -0.140 V, C = -0.126 V, D = -0.402V
The metal that displaces A from its aqueous solution is:

• A. B
• B. C
• C. D
• D. none of the above

Answer 1

Answer: (C)

D

Reduction potential of D is minimum i.e. $-0.402V$.Thus oxidation potential of D is maximum i.e. to $+0.402V$. D can oxidise itself and reduce other.
The aqueous solution A will be present in its ionic form and can be reduced by D as its reduction potential is higher than D.

Thus D can replace A from its Aqueous solution.