Question

why are decomposition reactions called the opposite of combination reactions?Write equations for these reactions.​

Answer 1

Decompression reactions are called the opposite of combination reactions because in combination reactions two reactants are combined to form a new compound while in decomposition reactions a compound splits to form it's constituents or simpler form.

example of combination reaction :-

C + O2 = CO2

example of decomposition reaction :-

CaCO3 = CaO + CO2

Answer 2

Combination reaction : A reaction in which 2 product combines and give 1 reactant

ex : mg + o give rise to mgO

Decomposition reaction : A reaction in which 1 product give rise to 2 reactant

ex : mgO give rise to mg + O