Which one of the following statements is correct

Options

A. Manganese salts give violet borax bead test in the reducing flame
B. From a mixed precipitate of `AgCl and AgI` ammonia solution dissolves only `AgCl`
C. Ferric ion give a deep green precipitate on adding potassium ferrocyanide solution
D. On boiling a solution having `K^(+),Ca^(2+)` and `HCO_(3)^(-)` ions we get a precipitate of `K_(2)Ca(CO_(3))_(2)`

Answer

To determine which statement is correct, we will analyze each statement provided regarding the behavior of certain compounds in specific conditions.

### Step-by-Step Solution:

1. **Understanding the Statements**:
- We have several statements regarding the behavior of compounds, particularly silver chloride (AgCl) and silver iodide (AgI) in the presence of ammonia.

2. **Analyzing the First Statement**:
- The first statement claims that "Magni salt gives violet borax bead test in the reducing flame."
- This statement is **incorrect** because Magni salt (which contains magnesium) does not produce a violet color in the borax bead test. Instead, it typically gives a colorless or white bead.

3. **Analyzing the Second Statement**:
- The second statement states that "from a mixed precipitate of AgCl and AgI, ammonia solution dissolves only AgCl."
- This statement is **correct**. Ammonia can dissolve AgCl to form a soluble complex ion, while AgI remains insoluble in ammonia.

4. **Analyzing the Third Statement**:
- The third statement is a repetition of the second statement and would also be considered correct based on the same reasoning.

5. **Analyzing the Fourth Statement**:
- The fourth statement is similar to the second and third statements, reiterating that ammonia solution dissolves only AgCl from the mixed precipitate.
- This statement is also **correct**.

6. **Conclusion**:
- Among the statements analyzed, the second statement is the one that is explicitly correct regarding the behavior of AgCl and AgI in ammonia solution.

### Final Answer:
The correct statement is: "From a mixed precipitate of AgCl and AgI, ammonia solution dissolves only AgCl."