Which of the following is not a prelminary test used to detect ions?

Options

A. Borax bead test
B. Flame test
C. Brown ring test
D. Microcosmic salt bead test

Answer

To solve the question of which of the following is not a preliminary test used to detect ions, we can follow these steps:

### Step 1: Understand the Concept of Preliminary Tests
Preliminary tests are initial tests that help to determine the presence of specific ions in a sample. They are typically quick and provide a preliminary indication of whether a particular ion is present.

### Step 2: Analyze the Options
We have four options to consider:
1. Borex bead test
2. Brown ring test
3. Ground ring test
4. Microsomic salt bead test

### Step 3: Identify the Nature of Each Test
- **Borex bead test**: This is a preliminary test used to detect certain metal ions based on their color changes when heated with a borax bead.
- **Brown ring test**: This test is specifically used to confirm the presence of nitrate ions (NO3-) or nitrite ions (NO2-). It is a confirmation test rather than a preliminary test.
- **Ground ring test**: This is another preliminary test used to detect certain ions.
- **Microsomic salt bead test**: This test is also used as a preliminary test for detecting specific ions.

### Step 4: Determine the Correct Answer
Since the Brown ring test is a confirmation test for nitrate and nitrite ions and not a preliminary test, the correct answer to the question is:
**Brown ring test** (Option 2).

### Final Answer
The option that is not a preliminary test used to detect ions is the **Brown ring test**.

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