Combination reaction and Decomposition reaction

Explanation

(i) When two or more reactants combine in a reaction to form a single product, it is called a combination reaction.
(ii) e.g.: When a Magnesium strip is burnt in air , it combines with oxygen, to form white ash of magnesium oxide.
(iii) `underset("Magnesium")(2Mg_((s)))+underset("Oxygen")(O_(2(g)))tounderset("Magnesium oxide")(2MgO_((s)))` (white ash)