A + B ---> AB.
A combination reaction can be of three types:
|a) Between two elements||C + O2 ? CO2||Carbon completely burnt in oxygen yields carbon dioxide|
|b) Between two compounds||2CaO + 2H2O ? 2Ca(OH)2||Calcium oxide (lime) combined with water gives calcium hydroxide (slaked lime)|
|c) Between an element and a compound||O2 + 2H2O ? 2H2O2||Oxygen (an element) combined with water (a compound) yields hydrogen peroxide|