Double Displacement Reaction:
A classic example of a double displacement reaction is the reaction between silver nitrate (AgNO3) and sodium chloride (NaCl) to form silver chloride (AgCl) and sodium nitrate (NaNO3). The chemical equation for this reaction is:
AgNO3 + NaCl → AgCl + NaNO3
In this reaction, the silver ion in silver nitrate combines with the chloride ion in sodium chloride to form a solid precipitate of silver chloride, while the sodium ion in sodium chloride combines with the nitrate ion in silver nitrate to form sodium nitrate.

Photochemical Reaction:
An example of a photochemical reaction is the reaction between chlorine gas (Cl2) and methane (CH4) in the presence of sunlight to produce chloromethane (CH3Cl) and hydrogen chloride (HCl). The chemical equation for this reaction is:
Cl2 + CH4 + light → CH3Cl + HCl
In this reaction, the chlorine gas is split into free radicals by sunlight, which then react with methane to form chloromethane and hydrogen chloride.

Thermal Decomposition Reaction:
An example of a thermal decomposition reaction is the decomposition of calcium carbonate (CaCO3) upon heating to form calcium oxide (CaO) and carbon dioxide (CO2). The chemical equation for this reaction is:
CaCO3 (s) → CaO (s) + CO2 (g)
In this reaction, calcium carbonate breaks down into calcium oxide and carbon dioxide when heat is applied.

Electrolytic Decomposition Reaction:
An example of an electrolytic decomposition reaction is the electrolysis of water (H2O) to produce hydrogen gas (H2) and oxygen gas (O2). The chemical equation for this reaction is:
2H2O (l) → 2H2 (g) + O2 (g)
In this reaction, water molecules are split into hydrogen and oxygen gases using an electric current.

Combination Reaction Between Two Compounds:
A combination reaction between two compounds is the reaction between iron (III) oxide (Fe2O3) and aluminum (Al) to form iron (Fe) and aluminum oxide (Al2O3). The chemical equation for this reaction is:
Fe2O3 + 2Al → 2Fe + Al2O3
In this reaction, aluminum displaces iron from iron (III) oxide to form iron and aluminum oxide.