Which of the following salts is used in the bead test for basic character ?

Options

A. `Na(NH_4)HPO_4. 4H_2O`
B. `Na_2HPO_4`
C. `(NH_4)_2SO_4.FeSO_4.6H_2O`
D. `(NH_3)_2HPO_4.2H_2O`

Answer

To solve the question regarding which salt is used in the bead test for basic character, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Bead Test**: The bead test, also known as the borax bead test, is a qualitative analysis technique used to identify certain metal ions in a sample. It involves heating a mixture of the sample with borax (sodium borate) to form a glassy bead.

2. **Identify the Purpose of the Test**: The primary purpose of the bead test is to determine the basic character of certain metal salts. When heated, these salts react with the borax to produce colored beads that indicate the presence of specific metals.

3. **Know the Common Salts Used**: The salts commonly used in the bead test include microcosmic salt, which is sodium ammonium hydrogen phosphate (NaNH4HPO4·4H2O). This salt is particularly known for its ability to form a colored bead when heated in the presence of certain metal ions.

4. **Select the Correct Option**: Among the options provided in the question, we need to identify which salt corresponds to the microcosmic salt used in the bead test. The correct answer is **microcosmic salt (NaNH4HPO4·4H2O)**.

5. **Conclude the Answer**: Therefore, the salt used in the bead test for basic character is microcosmic salt.

### Final Answer:
The salt used in the bead test for basic character is **microcosmic salt (NaNH4HPO4·4H2O)**.

---