Which one of the following compounds is not used as a reducing agent?

Identify the weakest oxidizing agent among the following.

While sulphur dioxide and hydrogen peroxide can act as oxidising as well as reducing agents in their reactions,ozone and nitric acid act only as oxidants. Why?

Consider the reaction $H_2SO_{3(aq)} + Sn^{4+}_{(aq)} + H_2O_{(l)} \to Sn^{2+}_{(aq)} + HSO_4^-(aq) + 3H^{+}_{(aq)}$. Which of the following statements is correct?

Acidized $KMnO_4$ solution does not oxidise:

Consider the reactions:
$(a)$ $H_3PO_{2(aq)} + 4AgNO_{3(aq)} + 2H_2O_{(l)} \to H_3PO_{4(aq)} + 4Ag_{(s)} + 4HNO_{3(aq)}$
$(b)$ $H_3PO_{2(aq)} + 2CuSO_{4(aq)} + 2H_2O_{(l)} \to H_3PO_{4(aq)} + 2Cu_{(s)} + H_2SO_{4(aq)}$
$(c)$ $C_6H_5CHO_{(l)} + 2[Ag(NH_3)_2]^+_{(aq)} + 3OH^-_{(aq)} \to C_6H_5COO^-_{(aq)} + 2Ag_{(s)} + 4NH_{3(aq)} + 2H_2O_{(l)}$
$(d)$ $C_6H_5CHO_{(l)} + 2Cu^{2+}_{(aq)} + 5OH^-_{(aq)} \to$ No change observed.
What inference do you draw about the behaviour of $Ag^+$ and $Cu^{2+}$ from these reactions?