Write the balanced chemical equations for the following reactions and identify the type of reaction in each case.
$(a)$ Chlorine gas is passed in an aqueous potassium iodide solution to form potassium chloride solution and solid iodine.
$(b)$ Ethanol is burnt in air to form carbon dioxide,water and releases heat.

(N/A) $2KI(aq) + Cl_2(g) \longrightarrow 2KCl(aq) + I_2(s)$
This is a displacement reaction because chlorine displaces iodine from potassium iodide.
$(b)$ $C_2H_5OH(l) + 3O_2(g) \longrightarrow 2CO_2(g) + 3H_2O(l) + \text{Heat}$
This is a combustion reaction,which is also a type of redox reaction,as ethanol reacts with oxygen to release energy.