Give a reason why:
$(i)$ Why is a decomposition reaction called the opposite of a combination reaction?

(N/A) In a decomposition reaction,a single substance [compound] breaks down to produce two or more simpler substances [elements or compounds].
Conversely,in a combination reaction,two or more substances [elements or compounds] combine to form a single new substance.
Because the processes involve opposite chemical changes—breaking down versus building up—a decomposition reaction is considered the opposite of a combination reaction.