Which one of the following molecules contain one lone pair of electrons on the central atom?

Options

A. `CH_4`
B. `NH_3`
C. `C Cl_4`
D. `H_2 O`

Explanation

To determine which of the given molecules contains one lone pair of electrons on the central atom, we will analyze the molecular structures of the options provided.

### Step-by-Step Solution:

1. **Identify the Molecules**: We need to analyze the following molecules:
- Methane (CH₄)
- Ammonia (NH₃)
- Carbon Tetrachloride (CCl₄)
- Water (H₂O)

2. **Analyze Methane (CH₄)**:
- The central atom is Carbon (C).
- Carbon has four valence electrons and forms four bonds with hydrogen atoms.
- The hybridization is sp³, resulting in a tetrahedral shape.
- There are **no lone pairs** on the central atom.

3. **Analyze Ammonia (NH₃)**:
- The central atom is Nitrogen (N).
- Nitrogen has five valence electrons and forms three bonds with hydrogen atoms.
- This leaves one lone pair of electrons on the nitrogen atom.
- The hybridization is also sp³, leading to a trigonal pyramidal shape.
- There is **one lone pair** on the central atom.

4. **Analyze Carbon Tetrachloride (CCl₄)**:
- The central atom is Carbon (C).
- Carbon has four valence electrons and forms four bonds with chlorine atoms.
- The hybridization is sp³, resulting in a tetrahedral shape.
- There are **no lone pairs** on the central atom.

5. **Analyze Water (H₂O)**:
- The central atom is Oxygen (O).
- Oxygen has six valence electrons and forms two bonds with hydrogen atoms.
- This leaves two lone pairs of electrons on the oxygen atom.
- The hybridization is sp³, leading to a bent shape.
- There are **two lone pairs** on the central atom.

6. **Conclusion**: Among the analyzed molecules, **Ammonia (NH₃)** is the only molecule that contains **one lone pair of electrons** on the central atom.

### Final Answer:
The molecule that contains one lone pair of electrons on the central atom is **Ammonia (NH₃)**.