Explain combination and decomposition reactions with suitable examples?

Combination Reaction:

1. A combination reaction occurs when two or more elements or compounds, known as reactants, react with each other and unite to produce a single chemical, known as the product.
2. These reactions can be represented as : $\mathrm{X}+\mathrm{Y}\to \mathrm{XY}$
3. A combination reaction refers to the reaction of two or more reactants to produce a single product.
4. The following is an example of a combination reaction: $\mathrm{MgO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)\to {\mathrm{MgCO}}_3\left(\mathrm{s}\right)$
5. Combination reactions can occur between two distinct chemicals, for as when magnesium oxide combines with carbon dioxide to form magnesium carbonate.

Decomposition Reaction :

1. It is a chemical process in which a single compound decomposes into two or more components.
2. These responses can be expressed as follows: $\mathrm{AB}\to \mathrm{A}+\mathrm{B}$
3. Because bond-breaking demands a lot of energy, these reactions are usually endothermic.
4. Hydrolysis of water is a basic example of a decomposition reaction in which a water molecule is broken down into hydrogen and oxygen gas.
5. The reaction may be written as : $2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2\mathrm{H}\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$