Decomposition reaction opposite of combination reaction because--1.In decomposition reaction a single compound break down into two or more products where as in combination reaction two or more compounds combined to form a single compound.2. example---># decomposition reaction-->CaCO3---->CaO+CO2,# combination reaction--->H2+Cl2--->2HCL

In chemistry, reactions can be classified into different categories based on their nature and type of reaction. Combination reactions involve the formation of a single compound from two or more reactants, whereas decomposition reactions involve the breakdown of a single compound into two or more products.


The decomposition of reactions is called the opposite of combination reactions because they involve the opposite process of combination. In combination reactions, two or more reactants combine to form a single product, whereas in decomposition reactions, a single compound breaks down into two or more products.


The general equation for a combination reaction is:

A + B → AB

Where A and B are the reactants and AB is the product. For example:

2Mg + O2 → 2MgO

This reaction involves the combination of magnesium and oxygen to form magnesium oxide.

The general equation for a decomposition reaction is:

AB → A + B

Where AB is the reactant and A and B are the products. For example:

2H2O → 2H2 + O2

This reaction involves the breakdown of water into hydrogen and oxygen gases.


The reason why decomposition reactions are called the opposite of combination reactions is that they involve the reverse process of combination. In a combination reaction, two or more reactants combine to form a single product, whereas in a decomposition reaction, a single compound breaks down into two or more products.

The process of decomposition can occur through a variety of mechanisms, including thermal decomposition, electrolysis, and photolysis. In thermal decomposition, the compound is broken down into its constituent elements through the application of heat. In electrolysis, the compound is broken down into its constituent ions through the application of an electric current. In photolysis, the compound is broken down through exposure to light.

Overall, the decomposition of reactions is an important process in chemistry as it allows for the breakdown of complex compounds into simpler products. This process is important in many chemical reactions, including the breakdown of organic compounds in biological systems and the decomposition of pollutants in the environment.