Which of the following has maximum bond angle ?
`H_(2)O,NH_(3),CO_(2),CH_(4)`
Give suitable explanation for your answer.

Answer

To determine which of the given molecules has the maximum bond angle among H₂O, NH₃, CO₂, and CH₄, we will analyze the molecular geometry and the bond angles of each compound based on the VSEPR (Valence Shell Electron Pair Repulsion) theory.

### Step 1: Analyze H₂O (Water)
- **Structure**: Water has a bent shape due to the presence of two lone pairs of electrons on the oxygen atom.
- **Bond Pairs**: There are 2 bond pairs (O-H bonds) and 2 lone pairs.
- **Bond Angle**: The bond angle in water is approximately 104.5°.
- **Explanation**: The presence of lone pairs causes greater repulsion compared to bond pairs, which reduces the bond angle.

### Step 2: Analyze NH₃ (Ammonia)
- **Structure**: Ammonia has a trigonal pyramidal shape due to one lone pair on the nitrogen atom.
- **Bond Pairs**: There are 3 bond pairs (N-H bonds) and 1 lone pair.
- **Bond Angle**: The bond angle in ammonia is approximately 107°.
- **Explanation**: The lone pair-bond pair repulsion is greater than bond pair-bond pair repulsion, resulting in a slightly larger bond angle than in water.

### Step 3: Analyze CO₂ (Carbon Dioxide)
- **Structure**: Carbon dioxide has a linear shape.
- **Bond Pairs**: There are 2 double bonds (C=O) and no lone pairs on the central carbon atom.
- **Bond Angle**: The bond angle in carbon dioxide is 180°.
- **Explanation**: In a linear molecule, the bond pairs are as far apart as possible, maximizing the bond angle.

### Step 4: Analyze CH₄ (Methane)
- **Structure**: Methane has a tetrahedral shape.
- **Bond Pairs**: There are 4 bond pairs (C-H bonds) and no lone pairs.
- **Bond Angle**: The bond angle in methane is approximately 109.5°.
- **Explanation**: All bond pairs are equally spaced, resulting in a bond angle that is larger than that of water and ammonia, but smaller than that of carbon dioxide.

### Conclusion
After analyzing the bond angles of all four molecules:
- H₂O: 104.5°
- NH₃: 107°
- CH₄: 109.5°
- CO₂: 180°

**The molecule with the maximum bond angle is CO₂, with a bond angle of 180°.**