Balance chemical equation to show how to convert: a.zinc carbonate to pure sample of zinc sulphate b.calcium oxide to a pure sample of calcium carbonate ?

##ZnCO_3(s) + H_2SO_4(aq) rarr ZnSO_4(aq) + CO_2(g) + H_2O(l)##

##CaO(s) + H_2O(l) rarr Ca(OH)_2(aq)##

##Ca(OH)_2(aq) + CO_2(g) rarr CaCO_3(s) + H_2O(l)##

Carbon dioxide is known to turn limewater (##Ca(OH)_2(aq)##, sparingly soluble in water) milky due to ##CaCO_3## precipitation.