Borax Bead Test is carried out when the original mixture is coloured. It is done with the help of a cleam platinum wire on which a small loop is made at the end. When borax is heated on platinum wire loop transparent glass like bead is obtained. The hot bead is brought in contact with salt till it reacts with fused borax and colour is imparted to the bead. bead colour is noted.
`{:("Colour of the bead","Ion"),(1." Blue green",Cu^(2+)),(2." Yellow ",Fe^(3+)),(3." Green",Cr^(3+)),(4." Violet",Mn^(2+)),(5." Dark blue",Co^(2+)),(6." Brown",Ni^(2+)):}`
Q. Glassy bead of :

Options

A. sodium tetraborate
B. sodium metaborate
C. sodium metabarate and boric anhydride
D. sodium tetraborate and boric anhydride

Explanation

To solve the question regarding the composition of the glassy bead formed during the borax bead test, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Borax Bead Test**:
- The borax bead test is a qualitative analysis technique used to identify certain metal ions based on the color of the bead formed when borax is heated and then mixed with the metal salt.

2. **Formation of the Bead**:
- When borax (sodium tetraborate) is heated on a platinum wire, it melts and forms a transparent glass-like bead.

3. **Composition of the Bead**:
- The glassy bead primarily consists of sodium metaborate (NaBO2) and boric anhydride (B2O3). These compounds are formed when borax is heated.

4. **Identifying the Components**:
- Sodium metaborate (NaBO2) is formed from the sodium ions and borate ions present in the borax.
- Boric anhydride (B2O3) is a result of the dehydration of boric acid, which is also related to the borax.

5. **Conclusion**:
- Therefore, the composition of the glassy bead can be expressed as a combination of sodium metaborate and boric anhydride.

6. **Final Answer**:
- The formula for the glassy bead is NaBO2 (sodium metaborate) and B2O3 (boric anhydride).