Question

Given that ${E^0}_{{O_2}/{H_2}O}$ = +1.23V
${E^0}_{{S_2}{O_8}^{2 - }/S{O_4}^{ - 2}}$= +2.05V
${E^0}_{B{r_2}/B{r^ - }}$= +1.09V
${E^0}_{A{u^{3 + }}/Au}$ = +1.4 V
The strongest oxidizing agent is:

A -{O_2} \\\ B -B{r_2} \\\ C -{S_2}{O_8}^{2 - } \\\ D -A{u^{3 + }} \\\ \end{gathered} $$

Answer 1

Oxidizing agents are those who oxidize others by reducing self. To be the strongest oxidizing agent species should have high standard reduction potential value.

Complete answer:
Standard reduction potential: A standard redox potential, symbol${E^o}$, is the electric potential of an electrochemical half-cell relative to a standard electrochemical half-cell (SHE) (hydrogen cell) under standard conditions (i.e. at 25$^0C$ at 1 atm pressure and 1 mol/l concentration). Standard redox potential is also known as the standard reduction potential.
Those which have positive value of standard reduction potential are oxidizing agents and those which have negative value of standard reduction potential are reducing agents. In both categories which have higher standard reduction potential value are the strong oxidizing agents and those who have lower standard reduction potential value are better reducing agents.
The given situation, standard reduction potential values of different electrochemical half-cells are given. Among them ${E^0}_{{S_2}{O_8}^{2 - }/S{O_4}^{ - 2}}$is the highest value of standard reduction potential i.e. +2.05V, so it has more oxidizing power and a better oxidizing agent.

Hence, the correct option is (C) ${S_2}{O_8}^{2 - }$.

Note: Among the given options all are having positive values of standard reduction potential so all are good oxidizing agents. Higher the positive value means higher tendency to accept electrons, i.e. good oxidizing agent.