Which of the following statements is/are correct ?

Options

A. An aqueous solution of `Co(II)` thiocyanate `(10%` freshly prepared) and mercuric nitrate solution taken in equal volumes on stirring the wall of the vessel with a glass rod produce deep-blue precipitate.
B. White precipitate of `Al(OH)_(3)` is soluble in sodium hydroxide as well as in ammonia solution
C. Green precipitate of `Cr(OH)_(3)` readily dissolves in excess of sodium hydroxide forming a green solution
D. Chromium (III) salts give green coloured borax bead in both oxidising and reducing flame.

Explanation

To determine which of the statements are correct, let's analyze each statement one by one:

### Step 1: Analyze the first statement
**Statement:** An aqueous solution of cobalt(II) thiocyanate (10 percent, freshly prepared) and mercuric nitrate solution taken in equal volumes on stirring the wall of the vessel with a glass rod produces a deep blue precipitate.

**Analysis:** This statement is correct. When cobalt(II) ions react with thiocyanate ions, they form a complex ion, specifically the cobalt(II) thiocyanate complex, which is known to produce a deep blue color. The reaction can be represented as:
\[ \text{Co}^{2+} + 2 \text{SCN}^- \rightarrow [\text{Co(SCN)}_2] \]
This complex is indeed deep blue in color.

### Step 2: Analyze the second statement
**Statement:** White precipitate of Al(OH)₃ is soluble in sodium hydroxide as well as ammonia solution.

**Analysis:** This statement is incorrect. The white precipitate of aluminum hydroxide (Al(OH)₃) is soluble in sodium hydroxide, forming a soluble complex ion:
\[ \text{Al(OH)}_4^- \]
However, it is not soluble in ammonia solution. Therefore, this statement is false.

### Step 3: Analyze the third statement
**Statement:** Green precipitate of chromium hydroxide readily dissolves in excess sodium hydroxide forming a green solution.

**Analysis:** This statement is correct. Chromium hydroxide (Cr(OH)₃) is a green precipitate that dissolves in excess sodium hydroxide to form a soluble complex:
\[ \text{Cr(OH)}_4^- \]
This results in a green solution, confirming that the statement is true.

### Step 4: Analyze the fourth statement
**Statement:** Chromium(III) salts give green colored borax bead test in both reducing and oxidizing flame.

**Analysis:** This statement is also correct. Chromium(III) ions form a green-colored complex when subjected to the borax bead test, producing chromium metaborate (CrBO₂) which appears green in both reducing and oxidizing flames.

### Conclusion
Based on the analysis:
- **Correct Statements:** 1, 3, and 4
- **Incorrect Statement:** 2

### Final Answer
The correct statements are 1, 3, and 4.

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