When $Zn$ is added to $CuSO_4$ solution,$Cu$ is obtained. This is due to:

In acid solution,the reaction $MnO_4^- \to Mn^{2+}$ involves

Explain redox reactions on the basis of electron transfer. Give suitable examples.

In the reaction $H_2S + NO_2 \to H_2O + NO + S$,$H_2S$ is

In the reactions given below,identify the species undergoing oxidation and reduction:
$(i)$ $H_{2}S_{(g)} + Cl_{2(g)} \rightarrow 2HCl_{(g)} + S_{(s)}$
$(ii)$ $3Fe_{3}O_{4(s)} + 8Al_{(s)} \rightarrow 9Fe_{(s)} + 4Al_{2}O_{3(s)}$
$(iii)$ $2Na_{(s)} + H_{2(g)} \rightarrow 2NaH_{(s)}$

In which of the following processes does nitrogen undergo oxidation?