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Question
In a locality, hard water, required for an experiment, is not available. However, the following salts are available in the school laboratory:
1. Sodium sulphate
2. Calcium sulphate
3. Magnesium chloride
4. Sodium chloride
5. Calcium chloride
6. Potassium sulphate
Which of the above salts may be dissolved in water to obtain hard water for the experiment?
(A) 2, 3 and 5
(B) 1, 2 and 5
(C) 1, 2, 4 and 6
(D) 3 and 5 only
Solution 1
Water containing calcium and magnesium salts is known as hard water. Among the given salts, calcium sulphate, magnesium chloride and calcium chloride can be dissolved in water to obtain hard water.
Hence, the correct option is A.
Solution 2
(A) 2, 3 and 5
Hard water is an impure form of water having high mineral contents like, Calcium, Magnesium, sulphides, chlorides, bicarbonates etc.
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