Find the odd one out with respect to the number of constituent atoms.

Options

A. Nitrogen pentoxide
B. Sulphuric acid
C. Calcium hydroxide
D. Ferric hydroxide

Explanation

To solve the problem of finding the odd one out with respect to the number of constituent atoms, we will analyze the molecular formulas of the given compounds and count the number of atoms in each.

### Step-by-Step Solution:

1. **Identify the Compounds and Their Molecular Formulas:**
- **Nitrogen Pentoxide:** N₂O₅
- **Sulfuric Acid:** H₂SO₄
- **Calcium Hydroxide:** Ca(OH)₂
- **Ferric Hydroxide:** Fe(OH)₃

2. **Count the Number of Atoms in Each Compound:**
- **Nitrogen Pentoxide (N₂O₅):**
- Nitrogen: 2 atoms
- Oxygen: 5 atoms
- Total: 2 + 5 = **7 atoms**

- **Sulfuric Acid (H₂SO₄):**
- Hydrogen: 2 atoms
- Sulfur: 1 atom
- Oxygen: 4 atoms
- Total: 2 + 1 + 4 = **7 atoms**

- **Calcium Hydroxide (Ca(OH)₂):**
- Calcium: 1 atom
- Oxygen: 2 atoms
- Hydrogen: 2 atoms
- Total: 1 + 2 + 2 = **5 atoms**

- **Ferric Hydroxide (Fe(OH)₃):**
- Iron: 1 atom
- Oxygen: 3 atoms
- Hydrogen: 3 atoms
- Total: 1 + 3 + 3 = **7 atoms**

3. **Compare the Total Number of Atoms:**
- Nitrogen Pentoxide: 7 atoms
- Sulfuric Acid: 7 atoms
- Calcium Hydroxide: 5 atoms
- Ferric Hydroxide: 7 atoms

4. **Identify the Odd One Out:**
- The compounds Nitrogen Pentoxide, Sulfuric Acid, and Ferric Hydroxide all have **7 atoms**.
- Calcium Hydroxide is the only compound with **5 atoms**.

### Conclusion:
The odd one out with respect to the number of constituent atoms is **Calcium Hydroxide (Ca(OH)₂)**.

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