There are four test tubes containing dilute `HCl, BaCl_(2), HgCl_(2) " and" KNO_(3)` solutions. Which of the following reagents will help in the identification of `BaCl_(2)` ?

Options

A. `NaOH`
B. `K_(2)CrO_(4)`
C. `AgNO_(3)`
D. both (2) and (3)

Explanation

To identify the presence of BaCl₂ (Barium Chloride) among the given solutions, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Compounds**: We have four solutions: dilute HCl, BaCl₂, HgCl₂, and KNO₃. Our goal is to identify BaCl₂.

2. **Select a Suitable Reagent**: We need a reagent that will react specifically with Ba²⁺ ions to form a distinct precipitate.

3. **Test with NaOH**: When BaCl₂ is treated with NaOH, it forms Ba(OH)₂, which is soluble in water. Therefore, there is no precipitate formed. This means NaOH is not useful for identifying BaCl₂.

**Hint**: Look for a reagent that forms an insoluble compound with Ba²⁺ ions.

4. **Test with K₂CrO₄**: When BaCl₂ is reacted with K₂CrO₄, barium chromate (BaCrO₄) is formed, which is a yellow precipitate. This indicates the presence of Ba²⁺ ions.

**Hint**: A color change or precipitate formation can indicate the presence of a specific ion.

5. **Test with AgNO₃**: If we react BaCl₂ with AgNO₃, a white precipitate of AgCl is formed, but this does not help in identifying BaCl₂ specifically as it does not produce a yellow precipitate.

**Hint**: Consider the color and solubility of the precipitate formed to confirm the identity of the compound.

6. **Conclusion**: The reagent that helps in identifying BaCl₂ is K₂CrO₄, as it produces a yellow precipitate of BaCrO₄.

**Final Answer**: K₂CrO₄ is the reagent that will help in the identification of BaCl₂.