In atmosphere, `SO_(2)` and `NO` are oxidised to `SO_(3)` and `NO_(2)`, respectively,w hcih react with water to given `H_(2)SO_(4)` and `HNO_(3)`. The resultant solution is called acid rain. `SO_(2)`dissolves in water to form diprotic acid.
`SO_(2)(g) +H_(2)O(l) hArr HSO_(3)^(Theta) + H^(o+), K_(a_(1)) = 10^(-2)`.
`HSO_(3)^(Theta) hArr SO_(3)^(2-) + H^(o+), K_(a_(2)) = 10^(-7)`
and for equilibrium,
`SO_(2)(aq) + H_(2)O (l) hArr SO_(3)^(2-)(aq) +2H^(o+)(aq)`
`K_(a) = K_(a_(1)) xx K_(a_(2)) = 10^(-9) at 300K`.
Which of the following reagnets will given white precipitate with the aqueous solution of sulphurous acid?

Options

A. `BaCI_(2)`
B. `HCI`
C. `NaCI`
D. `KCI`

Explanation

To solve the problem of which reagent will give a white precipitate with the aqueous solution of sulfurous acid (H₂SO₃), we can follow these steps:

### Step 1: Identify the nature of sulfurous acid
Sulfurous acid (H₂SO₃) is a diprotic acid that can dissociate in water to form bisulfite (HSO₃⁻) and sulfite (SO₃²⁻) ions. It is important to note that H₂SO₃ can react with certain metal ions to form insoluble salts.

### Step 2: Analyze the given reagents
The given reagents are:
- HCl
- NaCl
- KCl
- BaCl₂
- BaCl₃

We need to determine which of these reagents can react with H₂SO₃ to form an insoluble compound.

### Step 3: Identify the potential reaction
Barium chloride (BaCl₂) is known to react with sulfite ions (SO₃²⁻) to form barium sulfite (BaSO₃), which is an insoluble compound that precipitates out of solution. The reaction can be written as:
\[ \text{BaCl}_2 + \text{H}_2\text{SO}_3 \rightarrow \text{BaSO}_3 \downarrow + 2 \text{HCl} \]

### Step 4: Conclusion
Since BaSO₃ is insoluble in water and will precipitate as a white solid, the correct reagent that will give a white precipitate with the aqueous solution of sulfurous acid is **BaCl₂**.

### Final Answer
The correct option is **BaCl₂**.

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