Write the balanced chemical equations for the following and identify the type of reaction in each case :
(a) `"Barium"+"Potassium"to"Barium"+"Potassium"`
`"chloride (aq)"" ""sulphate (aq)"" ""sulphate (s)"" ""chloride (aq)"`
(b) `"Zinc carbonate (s)"to "Zinc oxide (s)"+ "Carbon dioxide (g)"`
(c ) `"Hydrogen (g)" + "Chlorine (g)"to "Hydrogen chloride (g)"`
(d) `"Magnesium (s)"+ underset("acid"(aq))("Hydrochloric")to underset("chloride"(aq))("Magnesium")+ "Hydrogen (g)"`

Explanation

(a) `2KBr(aq) + BaI_(2)(aq) to 2KI(aq) + BaBr_(2)(aq)`
The reaction is known as double displacement reaction.
(b) `ZnCO_(3)(s) to ZnO(s) + CO_(2)(g)`
The reaction is known as decomposition reaction.
(c) `H_(2)(g) + Cl_(2)(g) to 2HCl(g)`
The reaction is known as combination reaction
(d) `Mg(s) + 2HCl(aq) to MgCl_(2)(aq) + H_(2)(g)`
The reaction is known as displacement reaction.