A.KHCO<SUB>3</SUB>/H<SUB>2</SUB>CO<SUB>3</SUB>
B.NaHCO<SUB>3</SUB>/H<SUB>2</SUB>CO<SUB>3</SUB>
C.K<SUB>2</SUB>HPO<SUB>4</SUB>/KH<SUB>2</SUB>PO<SUB>4</SUB>
D.Na<SUB>2</SUB>HPO<SUB>4</SUB>/NaH<SUB>2</SUB>PO<SUB>4</SUB>
E.Na<SUB>2</SUB>CO<SUB>3</SUB>/NaHCO<SUB>3</SUB>