The hardness due to the presence of chlorides and sulphates of calcium an magnesium dissolved in it is called ……………. Hardness.

Explanation

**Step-by-Step Solution:**

1. **Understanding Water Hardness**: Water hardness refers to the concentration of dissolved minerals, primarily calcium and magnesium, in water. It can be classified into two main types: temporary hardness and permanent hardness.

2. **Identifying Types of Hardness**:
- **Temporary Hardness**: This type of hardness is mainly due to the presence of bicarbonates (HCO3-) of calcium and magnesium. It can be removed by boiling the water, which converts these bicarbonates into insoluble carbonates that precipitate out.
- **Permanent Hardness**: This type of hardness is caused by the presence of chlorides (Cl-) and sulfates (SO4^2-) of calcium and magnesium. Unlike temporary hardness, it cannot be removed by boiling.

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