Which of the following metal nitrate produces a gaseous product when it reacts with a $KCN$ solution?

The value of $x$ in the partial redox equation $MnO_4^- + 8H^{+} + xe^- \rightleftharpoons Mn^{2+} + 4H_2O$ is

In neutral or faintly alkaline medium,$KMnO_4$ being a powerful oxidant can oxidize thiosulphate almost quantitatively to sulphate. In this reaction,the overall change in the oxidation state of manganese will be:

$KMnO_4$ oxidises hydrogen sulphide in acidic medium. The number of moles of $KMnO_4$ which react with one mole of hydrogen sulphide is

For the balanced equation $NO_3^- + 4H^+ + ne^- \to 2H_2O + NO$,the value of $n$ is ........

Complete the following reactions:
$(a) \ Cr_2O_7^{2-} + X \to 2CrO_4^{2-} + H_2O$
$(b) \ Cr_2O_7^{2-} + 14H^+ + X \to 2Cr^{3+} + 7H_2O$
$(c) \ 6I^- \to X + 6e^-$