Which of the following element is nonmetal

Options

A. Gallium
B. Indium
C. Thalium
D. Boron

Answer

To determine which of the given elements is a non-metal, we will analyze each element listed: gallium, indium, thallium, and boron.

### Step-by-Step Solution:

1. **Identify the Elements**: The elements given are gallium (Ga), indium (In), thallium (Tl), and boron (B).

2. **Classify the Elements**:
- Gallium (Ga) is a post-transition metal.
- Indium (In) is also a post-transition metal.
- Thallium (Tl) is a metal.
- Boron (B) is classified as a metalloid, but it exhibits non-metallic properties.

3. **Analyze the Properties**:
- Metals typically have larger atomic sizes and tend to lose electrons easily to form positive ions.
- Non-metals have smaller atomic sizes and tend to gain or share electrons.

4. **Examine Boron's Characteristics**:
- Boron has a small atomic size (atomic number 5).
- Its electron configuration is 1s² 2s² 2p¹, indicating it has three valence electrons.
- Although boron can lose electrons, it does not behave like a typical metal due to its size and electronegativity.

5. **Conclusion**: Among the given elements, boron is the only one that exhibits non-metallic characteristics, making it the non-metal in this group.

### Final Answer:
**Boron (B) is the non-metal among the given elements.**

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