Four successive members of the first series of transition metals are listed below. For which one of the of standard potential `(E_(M^(2+)//M)^(@))` value has a positive sign ?

Options

A. Co(Z=27)
B. Ni(Z=28)
C. Cu(Z=29)
D. Fe(Z=26)

Answer

C

Explanation

In electrochemical series metals with positive standard potential are place below hydrogen. Out of given transition metals, only Cu is lower than hydrogen in electrochemical series. Therefore, it must have positive sign for standard potential.