Level of Hardness if the value is 50-150 mg/L ?
**Core Concept**
The question is testing the student's understanding of water hardness, specifically the classification based on the concentration of calcium and magnesium ions. Water hardness is a measure of the concentration of these ions in water, which affects its taste, color, and potential for scaling.
**Why the Correct Answer is Right**
Water hardness is typically classified into four categories: soft (less than 60 mg/L), moderately hard (60-120 mg/L), hard (120-180 mg/L), and very hard (more than 180 mg/L). Based on the given value of 50-150 mg/L, the water falls into the category of moderately hard. This classification is based on the total concentration of calcium and magnesium ions in the water.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a value of 0-30 mg/L would fall into the category of soft water.
**Option B:** This option is incorrect because a value of 200-300 mg/L would fall into the category of very hard water.
**Option C:** This option is incorrect because a value of 20-50 mg/L would fall into the category of soft water.
**Clinical Pearl / High-Yield Fact**
It's essential to note that water hardness can affect the scaling of water pipes and equipment, as well as the taste and color of the water. Moderately hard water, in particular, can lead to scaling and mineral buildup over time.
**Correct Answer: D. Moderately hard.**