Although both `CO_2` and `H_2O` are triatomic molecules, the shape of the `H_2O` molecule is bent while that of `CO_2` is linear. This is because

Options

A. C is less electronegative than H
B. C is more electronegative than H
C. lone pairs are present on O atom of `H_2O` but not in O atom Of `CO_2`
D. lone pairs carrying O is the central atom in `H_2O` but not in `CO_2`

Answer

To understand why the shapes of \( H_2O \) and \( CO_2 \) differ despite both being triatomic molecules, we need to analyze their molecular structures and the role of lone pairs in determining molecular geometry.

### Step-by-Step Solution:

1. **Identify the Molecular Structures**:
- **Water (\( H_2O \))**: The molecule consists of one oxygen atom bonded to two hydrogen atoms. Oxygen has two lone pairs of electrons.
- **Carbon Dioxide (\( CO_2 \))**: The molecule consists of one carbon atom double bonded to two oxygen atoms. Carbon has no lone pairs.

2. **Determine the Electron Geometry**:
- For \( H_2O \):
- The central atom is oxygen, which has 2 bonded pairs (from the two \( H \) atoms) and 2 lone pairs.
- The electron geometry is tetrahedral due to the four regions of electron density (2 bonds + 2 lone pairs).
- For \( CO_2 \):
- The central atom is carbon, which has 2 double bonds (one with each \( O \)) and no lone pairs.
- The electron geometry is linear because there are only 2 regions of electron density.

3. **Apply VSEPR Theory**:
- According to VSEPR (Valence Shell Electron Pair Repulsion) theory, lone pairs repel more strongly than bonded pairs.
- In \( H_2O \), the two lone pairs push the hydrogen atoms closer together, resulting in a bent shape.
- In \( CO_2 \), there are no lone pairs on the central atom (carbon), so the molecule maintains a linear shape.

4. **Conclusion**:
- The difference in shape arises from the presence of lone pairs on the oxygen atom in \( H_2O \), which causes repulsion and results in a bent structure, while \( CO_2 \) is linear due to the absence of lone pairs on the carbon atom.

### Final Answer:
The shape of \( H_2O \) is bent while that of \( CO_2 \) is linear because \( H_2O \) has two lone pairs on the central oxygen atom that cause repulsion, leading to a bent shape, whereas \( CO_2 \) has no lone pairs on the central carbon atom, resulting in a linear shape.