Presence of which of the following compounds make water hard. Na_(2)SO_(4),Ca(HCO_(3))_(2),MgCl_(2),Na_(2)CO_(3),CaSO_(4),KCl , NaHCO_(3),MgSO_(3),CaCl_(3)

Presence of which of the following compounds make water hard. Na_(2)SO

1.	Presence of which of the following compounds make water hard. Na_(2)SO_(4),Ca(HCO_(3))_(2),MgCl_(2),Na_(2)CO_(3),CaSO_(4),KCl , NaHCO_(3),MgSO_(3),CaCl_(3)
Answer» Solution :Five , i.e., `CA(HCO_(3))_(2), MgCl_(2),CaSO_(4), MgSO_(4), CaCl_(2)`