Drinking water mainly contains small amounts of salts of ______, ______ and ______ metals.

Explanation

To answer the question about the metals whose salts are mainly found in drinking water, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Context**: The question asks about the salts of certain metals that are commonly found in drinking water.

2. **Recall Common Salts in Water**: Drinking water often contains various minerals and salts. The most common ones include those from specific metals.

3. **List the Relevant Metals**:
- **Calcium (Ca)**: Calcium salts are commonly found in water and contribute to hardness.
- **Magnesium (Mg)**: Similar to calcium, magnesium salts are also present and contribute to the mineral content.
- **Sodium (Na)**: Sodium salts are often found in drinking water, especially in areas where water is treated with salt for softening.

4. **Formulate the Answer**: Based on the common knowledge of drinking water composition, we can conclude that drinking water mainly contains small amounts of salts of:
- Calcium (Ca)
- Magnesium (Mg)
- Sodium (Na)

### Final Answer:
Drinking water mainly contains small amounts of salts of **calcium (Ca)**, **magnesium (Mg)**, and **sodium (Na)** metals.

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