An aqueous solution of a white salt A gives a white precipitate B on treatment with dilute HCl in cold condition. B is soluble in boiling water. An aqeous solution of A gives a yellow precipitate on treatment with a solution of `K_(2)CrO_(4)`. The soda extract of A is acidified with diolute `H_(2)SO_(4)`, boiled to remove `CO_(2)` and treated with a freshly prepared solution of `FeSO_(4)`. concentratd `H_(2)SO_(4)` is added to the resulting solution. a brownn ring is formed at the junction of the two layers.
Q. The salt A is:

Options

A. `PbBr_(2)`
B. `Pb(NO_(3))_(2)`
C. `AgNO_(3)`
D. `Hg_(2)(NO_(3))_(2)`

Answer

To determine the identity of the white salt A, we can analyze the information provided step by step.

### Step-by-Step Solution:

1. **Identify the Reaction with Dilute HCl**:
- The problem states that an aqueous solution of the white salt A gives a white precipitate B when treated with dilute HCl in cold conditions.
- The formation of a white precipitate suggests that salt A could contain a metal that forms an insoluble chloride.

2. **Solubility of Precipitate B**:
- The precipitate B is described as being soluble in boiling water. This characteristic is important as it helps narrow down the possibilities.
- Lead(II) chloride (PbCl2) is a white precipitate that is soluble in hot water, which aligns with the description of precipitate B.

3. **Reaction with K2CrO4**:
- The next piece of information states that an aqueous solution of A gives a yellow precipitate when treated with K2CrO4.
- Lead(II) ions (Pb²⁺) react with potassium chromate (K2CrO4) to form lead(II) chromate (PbCrO4), which is a yellow precipitate. This confirms that lead ions are present in salt A.

4. **Soda Extract and Brown Ring Test**:
- The soda extract of A is acidified with dilute H2SO4, boiled to remove CO2, and treated with freshly prepared FeSO4.
- The addition of concentrated H2SO4 results in the formation of a brown ring at the junction of the two layers, which indicates the presence of nitrate ions (NO3⁻) in the solution. This is characteristic of the brown ring test for nitrates.

5. **Conclusion**:
- Based on the above reactions and observations, the white salt A is identified as lead(II) nitrate (Pb(NO3)2). This is consistent with all the reactions described.

### Final Answer:
The salt A is **Lead Nitrate (Pb(NO3)2)**.