Question

Which one is the wrong statement about electrochemical series?
A. Active metals have negative reduction potentials
B. Active non-metals have positive reduction potentials
C. Metals above hydrogen liberate hydrogen from acids
D. Metals below hydrogen are strong reducing agents

Answer 1

In an electrochemical series, the elements are arranged based on their increasing electrode potential values. With the help of electrochemical series we can predict the feasibility of the reaction, EMF of the cell, strength of oxidising and reducing agents.

Complete answer:
An electrochemical series is also known as the activity series. Therefore, the electrochemical series is the arrangement of elements in an order of their increasing reduction potential values. Here, the electrodes are arranged in increasing or decreasing order of their reduction potentials.
Now, let’s see some of the properties of the electrochemical series to find the right option:
According to the electrochemical series, the reduction potential of a particular element is considered in reference to the hydrogen scale where ${E_0} = 0$ potential. So, the reduction potential of an element can be described as the tendency of an element that undergoes reduction.
The higher the reduction potential the ease with which it can be further reduced. That means that the elements with lower reduction potential can be oxidized more quickly.
As we all know that the elements which lose electrons without any difficulty have a lower reduction potential and vice versa the elements have higher reduction potential.
The elements that have negative reduction potential or those who are situated below hydrogen in the electrochemical series are strong reducing agents and those which lie above hydrogen in the electrochemical series are weaker reducing agents.
While we move downwards on this electrochemical series the strength of the reducing agents increase whereas the strength of the oxidizing agents decreases.
Likewise, when we go downwards, the electro-positivity increases for metals and decreases for nonmetals.
After referring to the above features it is clear that the last option D. is the incorrect statement which says that metals below hydrogen are strong reducing agents.

Note: We must know that the electrochemical series is made up by arranging various redox equilibria in order of their standard electrode potentials (redox potentials). Therefore, the most negative $E^{o}$ values at the top of the electrochemical series, and the most positive at the bottom.