WAEC Chemistry 2017 Paper

Concept:Graphite and diamond are different allotropic forms of the same element, carbon.Explanation:Both graphite and diamond are made up of pure carbon atoms.Because their chemical composition is identical, they show similar chemical behaviour.When either form is heated strongly in oxygen, it burns completely to produce carbon(IV) oxide.The reaction is: $\mathrm{C_{(s)} + O_{2(g)} \rightarrow CO_{2(g)}}$.Diamond does not conduct electricity, but graphite does, so option D is not a common property.Their densities and external shapes are different, so options A and B are not shared properties.Thus, the similarity between graphite and diamond is their combustion to form carbon(IV) oxide.Answer:C. form carbon(IV) oxide on combustion.