$SnCl_2$ gives a precipitate with a solution of $HgCl_2$. In this process $HgCl_2$ is

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

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

What is an oxidation reaction? Explain it with an example.

When an acidified solution of ferrous ammonium sulphate is treated with potassium permanganate solution,the ion which is oxidised is

What is a reduction reaction? Give its examples.