This was a very popular question answered by the candidates and they performed very well in the (a) component of the question. However, some of the candidates could not answer the (b) component of the question well. The mode of formation of limestone rock is:
-           formed by the combination of calcium oxide (CaO) and carbon dioxide (CO2) to form calcium trioxocarbonate V (CaCO3)
-           formed from the remains of animals
            -           could have remains of plants
            -           formed under water
            -           animal matter is deposited either by wind, running water or glacier
            -           the materials are deposited in layers/strata
            -           numerous animals live in oceans and seas
-           when they die, their shells and skeleton drop to the sea bed
-           overtime, they are compacted to form rocks
-           such types of rocks are limestone
            -           when they are formed from animal matter they are called calcareous rocks
            -           when mixed with plant materials, they are called carboniferous limestone
            -           a region in which limestone is formed is called karst region