Write the balanced chemical equation for the following reaction and identify the type of reaction in each case. 

Magnesium ribbon is burnt in an atmosphere of nitrogen gas to form solid magnesium nitride. 

Write the balanced chemical equation for the following reaction and identify the type of reaction. 

Chlorine gas is passed in an aqueous potassium iodide solution to form potassium chloride solution and solid iodine. 

Name the substance oxidised, substance reduced, oxidising agent and reducing agent in the following reaction: 

${\mathrm{CuSO}}_4+\mathrm{Zn}\to \mathrm{Cu}+{\mathrm{ZnSO}}_4$

Name the substance oxidised, substance reduced, oxidising agent and reducing agent in the following reaction: 

$\mathrm{Cu}+2{\mathrm{AgNO}}_3\to \mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2+2\mathrm{Ag}$

In electrolytic decomposition reactions of water, why few drops of sulphuric acid are added to the water? 

In electrolytic decomposition reactions of water, name the gas produced at anode and cathode.

A blue coloured inorganic compound when heated with ${\mathrm{H}}_2\mathrm{S}$, gives black precipitate and an aqueous solution of sulphuric acid. Identify the compound. Give your answer with a balanced chemical equation.