Which Group IIIA elements is expected to have physical and chemical properties least similar to other members of that group?

Options

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

Answer

To determine which Group IIIA (or Group 13) element has physical and chemical properties least similar to the other members of that group, we need to analyze the elements in this group.

### Step-by-Step Solution:

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

2. **Classify the Elements**:
- Boron (B) is a nonmetal.
- Aluminum (Al), gallium (Ga), indium (In), and thallium (Tl) are metals.

3. **Compare Physical and Chemical Properties**:
- Boron exhibits nonmetallic properties such as being brittle and having a high ionization energy.
- The other elements (Al, Ga, In, Tl) are metallic in nature, showing properties like malleability, ductility, and good conductivity.

4. **Analyze Size and Ionization Energy**:
- Boron has the smallest atomic size in the group, which leads to a higher ionization energy compared to the other members.
- The charge density of boron is also higher due to its smaller size, which contributes to its unique properties.

5. **Conclusion**:
Since boron is a nonmetal and has significantly different physical and chemical properties compared to the metallic nature of the other elements in Group IIIA, it is expected to have properties least similar to the other members of the group.

### Final Answer:
The Group IIIA element expected to have physical and chemical properties least similar to the other members of that group is **Boron (B)**.

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