______ hardness is removed by Clark's method.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which type of hardness is removed by Clark's method.

2. **Identifying Clark's Method**: Clark's method is a specific technique used to treat water hardness. It is essential to know what this method entails.

3. **Types of Hardness**: Water hardness can be classified into two main types: temporary hardness and permanent hardness. Temporary hardness is primarily caused by the presence of bicarbonates of calcium and magnesium.

4. **Temporary Hardness**: Temporary hardness refers to the hardness that can be removed by boiling or by the addition of certain chemicals. It is mainly due to dissolved bicarbonates.

5. **Chemical Reaction in Clark's Method**: In Clark's method, lime (calcium hydroxide, Ca(OH)₂) is added to the water. The reaction that occurs is:
\[ \text{Ca(HCO}_3\text{)}_2 + \text{Ca(OH)}_2 \rightarrow \text{CaCO}_3 \downarrow + 2 \text{H}_2\text{O} \]
Here, calcium carbonate (CaCO₃) precipitates out of the solution, which helps in removing the hardness.

6. **Conclusion**: Since Clark's method effectively removes temporary hardness by precipitating calcium carbonate, the answer to the question is "temporary hardness".

**Final Answer**: Temporary hardness is removed by Clark's method.

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