Question

. Why is decomposition reactions called opposite of combination reactions? Write equations for these reactions.

Answer 1

Decomposition reaction is called the opposite of combination reaction because
In a combination reaction two or more substances are combined to form new substance while in the decomposition reaction one substance decomposes into two or more substances. Hence, the decomposition reactions are called opposite of combination reactions.

Combination reaction:- C + O2 -------> CO2
Decomposition reaction:- FeSO4-------> Fe2O3 + SO2 + O2

Answer 2

Decomposition reactions are called opposite of combination reaction because in decomposition reactions one compound breaks into two or more elements or compounds, whereas, in combination reaction more than one elements or compounds combine to form a compound.
Example: 2H2O------------> 2H2+O2(decomposition reaction)
2H2+O2-------> 2H2O(combination reaction)