When potassium iodide solution is added to a solution of lead $(II)$ nitrate in a test tube,a precipitate is formed.
$(i)$ Write a balanced chemical equation for this reaction.
$(ii)$ What type of reaction is this?

The following reaction is an example of a:
$4 NH_{3}(g) + 5 O_{2}(g) \rightarrow 4 NO(g) + 6 H_{2}O(g)$
$(i)$ Displacement reaction
$(ii)$ Combination reaction
$(iii)$ Redox reaction
$(iv)$ Neutralisation reaction

Complete and balance the following chemical equations:
$(i)$ $CaCO_{3} + HCl \longrightarrow$
$(ii)$ $Al + HCl \longrightarrow$
$(iii)$ $MnO_{2} + HCl \longrightarrow$

Identify the oxidising agent (oxidant) in the following reactions:
$(a) Pb_{3}O_{4} + 8HCl \longrightarrow 3PbCl_{2} + Cl_{2} + 4H_{2}O$
$(b) 2Mg + O_{2} \longrightarrow 2MgO$
$(c) CuSO_{4} + Zn \longrightarrow Cu + ZnSO_{4}$
$(d) V_{2}O_{5} + 5Ca \longrightarrow 2V + 5CaO$
$(e) 3Fe + 4H_{2}O \longrightarrow Fe_{3}O_{4} + 4H_{2}$
$(f) CuO + H_{2} \longrightarrow Cu + H_{2}O$

"$A$ solution of potassium chloride when mixed with silver nitrate solution, an insoluble white substance is formed".
$(i)$ Translate the above statement into a chemical equation.

What is the colour of $FeSO_{4} \cdot 7H_{2}O$ crystals? How does this colour change upon heating? Give the balanced chemical equation for the change.