The given reaction is an acid-base reaction (neutralisation) CaCO3 is a base, H3PO4 is an acid.
3CaCO3
Calciumcarbonate
+
2H3PO4
Phosphoricacid
⟶
Ca3(PO4)2
Calciumphosphate
+
3H2CO3
Carbonicacid
or
3CaCO3
Base
+
2H3PO4
acid
⟶Ca3(PO4)2+3CO2+3H2O Calcium carbonate reacts with phosphoric acid to produce calcium phosphate, carbon dioxide and water. Here, a=3,b=2,p=1,q=3,r=3 Now ratio of