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

Answer 1

The correct option is A

2,3, and 5

Hard water: As we all know, has a high mineral concentration and primarily comprises divalent cations. When water passes through limestone and gypsum salt deposits, it creates hard water.

1. We all know that water is normally clear, odorless, and tasteless, but it contains a variety of minerals and compounds, the presence of which influences the hardness and softness of the water.
2. Hardness is caused by minerals such as calcium and magnesium, which are found in water.
3. When water passes over calcium and magnesium-containing minerals such as limestone and gypsum, hard water is created.

Water hardness is divided into two categories: temporary and permanent hardness.

1. Temporary hardness is due to the presence of calcium bicarbonate and magnesium bicarbonate.
2. Permanent hardness is due to the presence of calcium sulfate or calcium chloride and magnesium sulfate or magnesium chloride.

So from the above explanation, we can say that water in laboratories can be made hard by using calcium chloride, calcium sulphate, and magnesium chloride.

Final Answer: Hence, the correct answer is option (A), Calcium sulphate Magnesium chloride, and Calcium chloride .