Question

why are decomposition reactions called the opposite of combination reactions . ​

Answer 1

Answer:

In combination reaction there is synthesis of two or more elements or compounds into a single compound.

Eg:2H2+O2=2H2O

Whereas in synthesis reaction there is decomposition of a single compund into two or more elements or compound.

Eg:2H2O=2H2+O2(When electricity is passed through one atom of water it dissociates into its elements hydrogen and oxygen)

So the decomposition reactions are called opposite of combination reactions.