Hardness of drinking water should be?
**Core Concept:** The concept being tested in this question is the ideal hardness level of drinking water and its relation to human health. Hard water contains excessive amounts of dissolved calcium and magnesium ions, which can lead to health issues when consumed in large quantities. Soft water has lower concentrations of these ions.
**Why the Correct Answer is Right:** The correct answer, **"C. 100-300 mg/L of calcium carbonate"**, represents the optimal range of calcium carbonate concentration in drinking water, which is around 100-300 mg/L. This range is considered safe for human consumption as it does not pose significant health risks.
**Why Each Wrong Option is Incorrect:**
A. **"5,000 mg/L"** is excessively high and can lead to several health problems like hypercalcaemia, kidney stones, and cardiac issues.
B. **"0 mg/L"** is too low, causing calcium deficiency which may cause muscle cramps, weak bones, and cardiovascular problems.
D. **"100-500 mg/L"** is too wide a range, and the optimal range (100-300 mg/L) is more precise and less likely to cause health concerns.
**Clinical Pearl:** Drinking water with a calcium carbonate concentration of 100-300 mg/L is considered safe and beneficial for maintaining overall health. The consumption of hard water (above 300 mg/L) or soft water (below 100 mg/L) can lead to various health issues. It is essential for individuals and public health authorities to ensure that the water supply meets the optimal range to minimize health risks.