Addition of iron filings to $CuSO_4$ solution causes the precipitation of $Cu$ due to the:

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

When copper turnings are added to silver nitrate solution,a blue coloured solution is formed after some time. It is because,copper

One of the phenomena which cannot be described as combustion is

During which of the following changes will an exchange of $5$ electrons take place?

When ammonia is heated with cupric oxide,each molecule of ammonia loses how many electrons?