Question

A standard hydrogen electrode has a zero potential because:
A) Hydrogen can be most easily oxidised
B) Hydrogen has only one electron
C) The electrode potential is assumed to be zero
D) Hydrogen is the lightest element

Answer 1

Hint:To solve this question, we must first understand some basic concepts about Standard Hydrogen Electrode. Then we need to assess the concept in such a way that we can conclude the proper required reason and then only we can conclude the correct answer.

Complete step by step answer
Before we move forward with the solution of this given question, let us first understand some basic concepts Standard Hydrogen Electrode:
Standard Hydrogen Electrode: (abbreviated SHE), is a redox electrode which forms the basis of the thermodynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be $4.44\, \pm 0.02\,\,V$ at \[25{\text{ }}^\circ C\] , but to form a basis for comparison with all other electrode reactions, hydrogen's standard electrode potential \[{\text{(E}}^\circ )\] is declared to be zero volts at any equilibrium. Potentials of any other electrodes are compared with that of the standard hydrogen electrode at the same temperature.
Hydrogen electrode is based on the redox half cell:
$2{H^ + }(aq)\,\, + \,\,2{e^ - }\,\, \to \,\,{H_2}(g)$
As we know that Potential is a relative term which means that it is always measured with respect to a reference. In electrochemistry, hydrogen is taken to be the reference to measure the potential and hence to form a basis for comparison with all other electrode reactions, hydrogen's standard electrode potential is declared or we can say that it is assumed to be zero volts at all temperatures.
So, clearly we can conclude that the correct answer is Option C.

Note:SHE is the basic guide for the reporting of the capacity of quantitative half-cells. It is a type of gas electrode and has been commonly used as a reference electrode and as an indicator electrode for calculating pH values in early studies.