Which one of the following has highest `m.pt` ?

Options

A. B
B. AI
C. Ga
D. Tl

Answer

To determine which element in the boron family has the highest melting point, we need to analyze the melting points of the members of Group 13 (the boron family). The members of this group include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl).

### Step-by-Step Solution:

1. **Identify the Members of the Boron Family**:
- The boron family consists of the following elements: Boron (B), Aluminum (Al), Gallium (Ga), Indium (In), and Thallium (Tl).

2. **Research the Melting Points**:
- We need to look up or recall the melting points of these elements:
- Boron (B): ~2075 °C
- Aluminum (Al): ~660 °C
- Gallium (Ga): ~30 °C
- Indium (In): ~157 °C
- Thallium (Tl): ~304 °C

3. **Compare the Melting Points**:
- Now, we compare the melting points:
- Boron: 2075 °C
- Aluminum: 660 °C
- Gallium: 30 °C
- Indium: 157 °C
- Thallium: 304 °C
- From this comparison, it is clear that Boron has the highest melting point.

4. **Reason for High Melting Point of Boron**:
- Boron has a high melting point because it is a covalent solid. Covalent solids typically have very high melting and boiling points due to the strong covalent bonds that hold the atoms together.

5. **Conclusion**:
- Therefore, the element with the highest melting point in the boron family is Boron (B).

### Final Answer:
**Boron (B) has the highest melting point among the members of the boron family.**

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