Which of the following species has tetrahedral geometry? A `BH_(4)^(-)` B `NH_(2)^(-)` C `CO_(3)^(2-)` D `H_(3)O^(+)`

Options

A. `BH_(4)^(-)`
B. `NH_(2)^(-)`
C. `CO_(3)^(2-)`
D. `H_(3)O^(+)`

Explanation

To determine which of the given species has a tetrahedral geometry, we need to analyze the hybridization and molecular geometry of each option.

### Step-by-Step Solution:

1. **Identify the species and their formulas:**
- A: `BH₄⁻`
- B: `NH₂⁻`
- C: `CO₃²⁻`
- D: `H₃O⁺`

2. **Determine the hybridization of each species:**
- **For `BH₄⁻`:**
- Boron (B) has 3 valence electrons and gains 1 from the negative charge, making a total of 4 valence electrons.
- It forms 4 bonds with hydrogen atoms.
- Hybridization: `sp³` (4 bond pairs, 0 lone pairs).
- Geometry: Tetrahedral.

- **For `NH₂⁻`:**
- Nitrogen (N) has 5 valence electrons and gains 1 from the negative charge, making a total of 6 valence electrons.
- It forms 2 bonds with hydrogen atoms and has 2 lone pairs.
- Hybridization: `sp³` (2 bond pairs, 2 lone pairs).
- Geometry: Bent.

- **For `CO₃²⁻`:**
- Carbon (C) has 4 valence electrons and gains 2 from the negative charge, making a total of 6 valence electrons.
- It forms 3 bonds with oxygen atoms and has 1 lone pair.
- Hybridization: `sp³` (3 bond pairs, 1 lone pair).
- Geometry: Trigonal pyramidal.

- **For `H₃O⁺`:**
- Oxygen (O) has 6 valence electrons and loses 1 due to the positive charge, making a total of 5 valence electrons.
- It forms 3 bonds with hydrogen atoms and has 1 lone pair.
- Hybridization: `sp³` (3 bond pairs, 1 lone pair).
- Geometry: Trigonal pyramidal.

3. **Conclusion:**
- The only species with tetrahedral geometry is `BH₄⁻` (Option A).

### Final Answer:
The species that has tetrahedral geometry is **A: `BH₄⁻`**.

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