In Borax bead test, metal oxides react with `B_(2)O_(3)` and form a coloured bead. This bead contains

Options

A. orthoborate ion
B. metaborate ion
C. double oxide
D. tetraborate ion

Answer

**Step-by-Step Solution:**

1. **Understanding the Borax Bead Test**: The Borax bead test is a qualitative analysis method used to identify certain metal ions based on the color of the bead formed when metal oxides react with boron oxide (B2O3).

2. **Reaction of Metal Oxides with B2O3**: When a metal oxide (like copper oxide, CuO) is heated with boron oxide, it forms a colored bead. The metal oxide reacts with B2O3 to form a metaborate compound.

3. **Identifying the Colored Bead**: For example, when copper oxide (CuO) reacts with B2O3, it forms a blue-colored bead. The chemical formula for the resulting compound is typically represented as Cu(BO2)2, where BO2 represents the metaborate ion.

4. **Conclusion**: The colored bead formed in the Borax bead test contains the metaborate ion (BO2^-). Therefore, the answer to the question is that the bead contains metaborate ion.

5. **Final Answer**: The bead contains metaborate ion.

---