Question

What causes hardness in water?

Answer 1

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=>The two main cations that cause water hardness are calcium (Ca2+) and magnesium (Mg2+). Calcium is dissolved in water as it passes over and through limestone deposits. Magnesium is dissolved as waterpasses over and through dolomite and other magnesium bearing formations.

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Answer 2

due to presence of ca and mg salt of sulphate carbonate bicarbonate chloride the water become hard and not produce lather with soap .i think it help you