Question

Why are decomposition reaction called the opposite combination reaction write equation for these reactant?

Answer 1

Decomposition reaction are called the opposite of combination reaction because -
In combination reaction,
two or more reactants combine to form a single product.
Example- C(s) + O2(g) -------2MgO + heat
Whereas in decomposition reaction,
a single reactant breaks down to give simpler products.
Example- CaCO3(s) + heat ------ CaO (s)+ CO2(g).