Why are decomposition reactions called the opposite of combination reactions ? Write equations for these reactions.

Explanation

In decompositon reaction, a single compound splits to give rise to two or more simple substance. In combination reaction, two or more simpler substance combine together to form a single compound. Hence they are opposite to each other .
Example of decomposition reactions :
`underset("Copper carbonate")(CuCO_(3(s))) overset("Heat")to underset("Copper oxide")(CuO_((s))) + underset("Carbondioxide")(CO_(2(g)))`
Example of combination reaction.
`underset("Magnesium")(2Mg_((s))) + underset("Oxygen")(O_(2(g))) overset("heat")to underset("Magnesium oxide")(2MgO_((s)))`