In case of a standard hydrogen electrode

In case of a standard hydrogen electrode

absolute electrode potential is not zero
absolute electrode potential is zero
both absolute and standard electrode potential values are zero
electrode potential is zero only at 25°C
This question was previously asked in
UPSC CDS-2 – 2016
The absolute electrode potential of a standard hydrogen electrode (SHE) is not zero.
By international convention, the *standard electrode potential* of the SHE is *defined* as zero volts (0 V) at standard conditions (typically 25°C, 1 bar/atm H₂ pressure, and 1 M H⁺ concentration). This defines a relative scale for measuring the standard potentials of other half-cells. However, the absolute potential of the SHE, which represents the potential difference between the electrode and a point infinitely far away in vacuum, is not zero and is estimated to be around +4.44 V at 25°C.
The ability to measure absolute electrode potentials is limited; therefore, a reference electrode with a defined potential, like the SHE, is used to create a relative potential series. Option D is misleading as the zero potential is defined at standard conditions including 25°C, but the phrasing “only at 25°C” is inaccurate and incomplete regarding the conditions.
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