2016 · Q28
In case of a standard hydrogen electrode
General KnowledgeChemistry
- Aabsolute electrode potential is not zero
- Babsolute electrode potential is zero
- Cboth absolute and standard electrode potential values are zero
- Delectrode potential is zero only at 25 °C
Explanation
The standard hydrogen electrode is assigned an electrode potential of exactly zero by convention, and that assignment is defined at standard state — 25 °C, 1 atm H2, unit H+ activity — so the intended answer is (d): the zero holds only at 25 °C. Strictly, the absolute (vacuum-referenced) potential of the SHE is not zero (about 4.4 V), which makes option (a) defensible too. Note: key disputed — verify against the official UPSC key.