Which of the reactions occurs at the anode during the electrolysis of a very dil...

During the electrolysis of a very dilute aqueous solution of sodium chloride (NaCl), the reaction that occurs at the anode is the oxidation of hydroxide ions (OH^-) to form hydroxyl radicals (OH) and electrons (e^-). This is represented by the equation:

\[\text{OH}^- - e^- \rightarrow \text{OH}\]

This is Option A in the question. The reason for this is because in a very dilute solution, there is a higher concentration of water molecules compared to sodium and chloride ions. The water molecules undergo self-ionization to form hydronium ions (H₃O⁺) and hydroxide ions (OH^-).

At the anode, which is the positive electrode, negatively charged ions (anions) are attracted to it. In this case, both chloride ions (Cl^-) and hydroxide ions (OH^-) are present in the solution. However, due to the higher concentration of water, the hydroxide ions are preferentially oxidized over the chloride ions.

It is important to note that in a more concentrated solution of sodium chloride, the chloride ions would be preferentially oxidized at the anode, resulting in the formation of chlorine gas (Cl₂).