The absolute value of the electrode potential cannot be determined experimentally.
Reason: The electrode potentials are generally determined with respect to standard hydrogen electrodes.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct bur Reason is incorrect,
D. Assertion is incorrect but Reason is correct.

Hint: The potential of an unknown electrode can be determined by using standard hydrogen electrode by taking as reference because the potential of standard hydrogen electrode is zero. Standard hydrogen electrode also called SHE.

Complete step by step answer:
- In the question there are two statements, one statement is under assertion and the other statement is under reason.
- We have to find whether assertion and reason statements are correct or not and we have to check whether reason is the correct explanation for assertion or not.
- Coming to Assertion, The absolute potential value of a single electrode cannot be determined experimentally because the half-cell reaction does not take place alone.
- We can find the difference between the electrode potentials of two different half-cells by connecting them.
-Therefore the Assertion is correct.

-Coming to Reason, the electrode potentials are generally determined with respect to standard hydrogen electrodes.
- The statement in reason is also correct. By using SHE we can find the potentials easily.
- But the reason is not a correct explanation for Assertion.
- Therefore, both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
So, the correct answer is “Option B”.

Note: In the electrochemical series all the potentials of the different electrodes are tabulated. Those potentials are calculated by connecting them to standard hydrogen electrodes only. In Electrochemistry SHE plays a vital role.