Concentrated HCl cannot be used as group reagent in first group precipitation. Why ?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks why concentrated HCl cannot be used as a group reagent for the precipitation of first group elements in qualitative analysis.

2. **Identifying the Group Reagent**: In qualitative analysis, group reagents are used to precipitate specific ions from a solution. For the first group, we typically use dilute hydrochloric acid (HCl) to precipitate metal chlorides.

3. **Effect of Concentrated HCl**: When concentrated HCl is added, it dissociates into H⁺ and Cl⁻ ions. The high concentration of Cl⁻ ions can lead to the formation of soluble complex ions instead of precipitating the desired metal chlorides.

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