Which of the following elements is the best oxidizing agent?

When $SO_2$ is passed through an acidified solution of $H_2S$,what happens?

Explain why ozone $(O_3)$ is thermodynamically less stable than oxygen $(O_2)$?

Given below are two statements:
Statement $I$: Oxygen being the first member of group $16$ exhibits only $-2$ oxidation state.
Statement $II$: Down the group $16$ stability of $+4$ oxidation state decreases and $+6$ oxidation state increases.
In the light of the above statements,choose the most appropriate answer from the options given below:

Which one of the following is most acidic?

At what temperature does dioxygen gas liquefy and at what temperature does it freeze?