Assertion : Absolute value of $E_{red}^0$ of an electrode cannot be determined.

Reason    : Neither oxidation nor reduction can take place alone.

Only $E_{red}^0$ w.r.t a reference electrode can be determined.

Assertion: "Absolute value of ${\mathrm{E}}_{\mathrm{red}}^{°}$ of an electrode cannot be determined."

• The standard reduction potential (${\mathrm{E}}_{\mathrm{red}}^{°}$) is a measure of the tendency of an electrode to undergo reduction (gain electrons) under standard conditions (1 M concentration, 1 atm pressure, and 298 K temperature). It helps to compare the relative strengths of different half-reactions.
• The assertion suggests that the absolute value of ${\mathrm{E}}_{\mathrm{red}}^{°}$ cannot be determined. This might be due to the fact that ${\mathrm{E}}_{\mathrm{red}}^{°}$ values are typically measured relative to a reference electrode, such as the standard hydrogen electrode (SHE), which is assigned an arbitrary value of 0 V.

Reason: "Neither oxidation nor reduction can take place alone."

• This reason highlights the fact that most electrochemical reactions involve both oxidation (loss of electrons) and reduction (gain of electrons) reactions, occurring simultaneously. This is known as a redox (reduction-oxidation) reaction.
• In a redox reaction, one species loses electrons (undergoes oxidation) while another species gains electrons (undergoes reduction). This is required to maintain charge neutrality in the overall chemical reaction.

Analysis Conclusion:

The reason provided is valid: Neither oxidation nor reduction can occur alone in a redox reaction. However, the assertion is not entirely accurate. While the absolute value of the standard reduction potential (${\mathrm{E}}_{\mathrm{red}}^{°}$) is measured relative to a reference electrode, it can still be determined within the context of electrochemical measurements and comparisons between different half-reactions.

It's also worth noting that the standard reduction potential (${\mathrm{E}}_{\mathrm{red}}^{°}$) is a thermodynamic property and provides information about the potential energy change associated with a specific redox reaction. In practice, electrochemists often measure and tabulate ${\mathrm{E}}_{\mathrm{red}}^{°}$ values to predict the feasibility and direction of electrochemical reactions