Melting point is highest for

Options

A. B
B. AI
C. Ga
D. In

Explanation

To determine which element has the highest melting point among the group 3A elements, we can analyze the melting points of the elements in this group: boron, aluminum, gallium, indium, and thallium.

### Step-by-Step Solution:

1. **Identify the Elements in Group 3A**:
The elements in group 3A (or group 13 of the periodic table) include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl).

2. **List the Melting Points**:
- Boron (B): 2075 °C
- Aluminum (Al): 660 °C
- Gallium (Ga): 29.76 °C
- Indium (In): 1566 °C
- Thallium (Tl): 304 °C

3. **Compare the Melting Points**:
By comparing the melting points of these elements, we can see that boron has the highest melting point at 2075 °C, followed by indium at 1566 °C, thallium at 304 °C, aluminum at 660 °C, and gallium at 29.76 °C.

4. **Conclusion**:
Therefore, the element with the highest melting point among the group 3A elements is **boron**.

5. **Reason for High Melting Point**:
Boron has a very strong crystalline lattice structure, which requires a higher temperature to break the bonds and melt the solid. In contrast, the other elements in this group are softer metals with lower melting points and higher electrical conductivity.

### Final Answer:
The melting point is highest for **boron**.

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