Borax bead test is responded by :

Options

A. divalent metals
B. heavy metals
C. light metals
D. metals which form coloured metaborates.

Answer

To solve the question regarding which type of metal ions respond to the borax bead test, we can follow these steps:

### Step 1: Understand Borax
Borax is a compound with the formula Na2B4O7·10H2O. When heated, it loses water and forms sodium tetraborate (Na2B4O7) and then further decomposes to sodium metaborate (NaBO2) and boric anhydride (B2O3).

### Step 2: Heating Process
Upon heating, borax first loses its water molecules, swells into a white porous mass, and then melts into a colorless liquid, forming a clear transparent glass bead. This bead consists of sodium metaborate and boric anhydride.

### Step 3: Reaction with Metal Salts
When this borax bead is heated with colored metallic salts, a characteristic colored bead of metal metaborate is formed. The color of the bead depends on the metal ion present in the salt.

### Step 4: Identify Metal Types
The metals that can respond to the borax bead test are those that form colored metaborates. This includes various heavy metals and some divalent metals. However, the key requirement is that the metal must be capable of forming a colored compound when reacting with boric anhydride.

### Step 5: Conclusion
From the analysis, we conclude that the borax bead test is specifically responded to by metals that can form colored metaborates. Therefore, the correct answer to the question is:

**Metals which can form colored metaborates.**

### Final Answer:
The borax bead test is responded by metals which can form colored metaborates.

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