Question

why are decomposition reaction called the opposite of combination reaction?write the equation for this reaction.

Answer 1

Hey...!!!
In decomposition rxn compounds break into the corresponding reactants...
&
In combination rxn corresponding reactants combine to form products...
Eg..
Na + Cl => NaCl

NaCl(on heating) => Na + Cl...

Hope this helps you... ☺️☺️

Answer 2

In combination reaction ,two atom,ion or molecules combine to form a product,whereas in decomposition reaction one compound break into two or more ion,atom or molecules.
for eg.
CaCO3 -----> CaO+ CO2