Question

Match the following reactions with their respective types of reactions .

• A. Combination
• B. Decomposition
• C. Displacement

Answer 1

Burning of magnesium is a combination reaction as magnesium combines with oxygen to give magnesium oxide.

$2\text{Mg(s)}+{\text{O}}_2\text{(g)}\to \text{2MgO(s)}$

Heating of calcium carbonate gives calcium oxide and carbon dioxide, which is a decomposition reaction.

$2{\text{CaCO}}_3\text{(s)}\to \text{2CaO(s)}+{\text{CO}}_2\text{(g)}$

When magnesium is treated with HCl, it displaces hydrogen from HCl and forms ${\text{MgCl}}_2$. Hence, it is a displacement reaction.

$\text{Mg(s)}+\text{2HCl(aq)}\to {\text{2MgCl}}_2\text{(aq)}+{\text{H}}_2\text{(g)}$