Identify the reductant in the following reaction: $C_2O_4^{2-} + MnO_4^{-} + H^{+} \longrightarrow Mn^{2+} + CO_2 + H_2O$

Which among $KI, FeSO_4, K_2MnO_4, KMnO_4$ cannot be oxidised by $O_3$?

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?

Which of the following elements never acts as a reducing agent in a chemical reaction?

Which of the following is not a reducing agent?

Which of the following species acts as the strongest oxidising agent?