Question

Which of the following cannot form the inner reference electrode in glass electrodes?

(a) Silver electrode

(b) Copper electrode

(c) Calomel electrode

(d) Silver chloride electrode

This question was addressed to me in a job interview.

The origin of the question is Hydrogen and Glass Electrodes topic in section pH Meters and Ion Analysers of Analytical Instrumentation

Answer 1

Right answer is (b) Copper electrode

To elaborate: Copper electrode cannot form the inner reference electrode in glass electrodes. Inner reference electrode is immersed in a buffer solution.