Which of the following statements is /are true ?

Options

A. `Ag^(+)` ions do not give white precipitate with excess of concentrated `HCl`
B. `Cu^(2+)` ions produce a white precipitate when `KCN` solution is added in a small quantity.
C. `Hg^(2+)` ions give deep blue precipitate with cobalt acetate and ammonium thiocyanate.
D. Black precipitate of `Bil_(3)` turns orange when heated with water.

Explanation

To determine which of the statements are true, we will analyze each statement step by step.

### Step 1: Analyze Statement 1
**Statement:** Ag⁺ ions when dissolved, give a white precipitate with excess of concentrated HCl.

**Analysis:**
- When Ag⁺ ions are treated with limited HCl, they form AgCl, which is a white precipitate.
- However, when excess HCl is present, AgCl can dissolve to form a soluble complex, [AgCl₂]⁻.
- Therefore, Ag⁺ ions do not give a white precipitate in excess HCl.

**Conclusion:** Statement 1 is **False**.

### Step 2: Analyze Statement 2
**Statement:** Cu²⁺ ions produce a white precipitate with KCN solution when added in small quantity.

**Analysis:**
- When Cu²⁺ ions react with CN⁻ ions (from KCN), they form Cu(CN)₂, which is a white precipitate.
- This reaction occurs in small quantities of KCN.

**Conclusion:** Statement 2 is **True**.

### Step 3: Analyze Statement 3
**Statement:** Hg²⁺ ions give a deep blue precipitate with cobalt acetate and ammonium thiocyanate.

**Analysis:**
- When Hg²⁺ ions react with cobalt acetate and ammonium thiocyanate, they form a complex that has a deep blue color.
- The complex formed is [Hg(SCN)₂] and exhibits a deep blue color.

**Conclusion:** Statement 3 is **True**.

### Step 4: Analyze Statement 4
**Statement:** Black precipitate of bismuth iodide turns orange when heated with water.

**Analysis:**
- Bismuth iodide (BiI₃) is indeed a black precipitate.
- However, it does not turn orange when heated with water. Instead, it turns orange when treated with excess iodide ions.
- Therefore, the statement is incorrect as it specifies heating with water instead of excess iodide.

**Conclusion:** Statement 4 is **False**.

### Final Conclusion
- **True Statements:** 2 and 3.
- **False Statements:** 1 and 4.

### Summary of True Statements:
- Statement 2 is true: Cu²⁺ ions produce a white precipitate with KCN.
- Statement 3 is true: Hg²⁺ ions give a deep blue precipitate with cobalt acetate and ammonium thiocyanate.