WAEC Chemistry 2011 Paper

Concept:Limestone ($\mathrm{CaCO_3}$) acts as a raw material or flux in many industrial processes. We need to identify the process that does not use it.Explanation:A. In the extraction of iron in the blast furnace, limestone is used as a flux to remove impurities as slag.B. The Contact process uses sulphur, oxygen and vanadium(V) oxide as a catalyst; limestone is not required.C. The Solvay process for washing soda uses limestone to produce $\mathrm{CO_2}$ and quicklime ($\mathrm{CaO}$).D. Cement production uses limestone as the main raw material.Answer:The process that does not involve limestone is the manufacture of tetraoxosulphate(VI) acid ($\mathrm{H_2SO_4}$) by the Contact process (Option B).