Question

Why decomposition reaction called opposite of combination reaction ? Write equation for these reactions

Answer 1

it's known as the opposite cause combination reaction is when two or more elements together forms a single compound..but in decomposition reaction,a single compound breaks to form two or more elements..

2Fe + S = FeS (combination reaction)

2HgO =  2Hg + O2 (decomposition reaction)

Answer 2

It is because in combination reaction two elements combine to form a compound but in decomposition reaction one compound splits into two elements example dor each is:

Na + O2 -》Na2O

Agcl -》Ag +CL2