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

• (a) Potassium bromide (aq) + Barium iodide (aq) \(\rightarrow \) Potassium iodide (aq) + Barium bromide(s)
• (b) Zinc carbonate(s) \(\rightarrow \) Zinc oxide(s) + Carbon dioxide(g)
• (c) Hydrogen(g) + Chlorine(g) \(\rightarrow \) Hydrogen chloride(g)
• (d) Magnesium(s) + Hydrochloric acid(aq) \(\rightarrow \) Magnesium chloride(aq) + Hydrogen(g)

$$ (a) \;\;\; 2KBr(aq) + BaI_{2}(aq) $$

$$ \downarrow$$

$$ \;\;\; 2KI(aq) + BaBr_{2} $$

It is a Double Decomposition Reaction.
This is a type of chemical change in which two compounds in a solution react to form two new compounds by mutual exchange of radicals.It is also called double displacement reaction.

$$(b) ZnCO_{3}(s) \rightarrow ZnO(s) + CO_{2}(g) $$
It is Decomposition reaction.
The chemical reaction in which a compound splits into two or more simpler substances (elements or compounds) is called decomposition reaction.

$$(c) H_{2}(g) + Cl_{2}(g) \rightarrow 2HCl $$
It is a Direct Combination reaction.
A reaction in which two or more substances combine together to form a single substance is called a combination reaction or synthesis.

$$(d) \;\;\; Mg(s) + 2HCl(aq) $$

$$ \downarrow$$

$$ \;\;\; MgCl_{2} (aq) + H_{2}(g) $$

It is a Displacement reaction.
It is a chemical change in which a more active element displaces a less active element from its salt solution.