Polarity in a molecule and hence the dipole moment depends primarily on electronegativity of the constituent atoms and shape of a molecule. Which of the following has the highest dipole moment?

Options

A. `CO_(2)`
B. HI
C. `H_(2)O`
D. `SO_(2)`

Explanation

To determine which molecule has the highest dipole moment, we need to analyze the given molecules based on their structure, electronegativity, and the presence of lone pairs. Here’s a step-by-step solution:

### Step 1: Understand the concept of dipole moment
The dipole moment (\( \mu \)) is a measure of the separation of positive and negative charges in a molecule. It is influenced by the electronegativity of the atoms involved and the molecular geometry. The formula for dipole moment is given by:
\[ \mu = Q \times D \]
where \( Q \) is the charge and \( D \) is the distance between the charges.

### Step 2: Analyze the given molecules
We will consider the following molecules:
1. Carbon Dioxide (CO₂)
2. Hydrogen Iodide (HI)
3. Water (H₂O)
4. Sulfur Dioxide (SO₂)

### Step 3: Evaluate Carbon Dioxide (CO₂)
- **Structure**: CO₂ is a linear molecule.
- **Polarity**: The molecule has two polar bonds (C=O) that are equal in magnitude but opposite in direction. Therefore, they cancel each other out.
- **Dipole Moment**: The dipole moment of CO₂ is zero.

### Step 4: Evaluate Hydrogen Iodide (HI)
- **Structure**: HI is a diatomic molecule.
- **Polarity**: HI has a polar bond due to the difference in electronegativity between H and I.
- **Dipole Moment**: HI has a dipole moment of approximately 0.38 D.

### Step 5: Evaluate Water (H₂O)
- **Structure**: Water has a bent molecular shape due to the two lone pairs on the oxygen atom.
- **Polarity**: The O-H bonds are polar, and the bent shape means the dipole moments do not cancel out.
- **Dipole Moment**: Water has a dipole moment of approximately 1.84 D.

### Step 6: Evaluate Sulfur Dioxide (SO₂)
- **Structure**: SO₂ has a bent shape due to one lone pair on sulfur.
- **Polarity**: The S=O bonds are polar, and the bent shape means the dipole moments do not cancel out.
- **Dipole Moment**: SO₂ has a dipole moment of approximately 1.61 D.

### Step 7: Compare the dipole moments
Now, we can compare the dipole moments of the four molecules:
- CO₂: 0 D
- HI: 0.38 D
- H₂O: 1.84 D
- SO₂: 1.61 D

### Conclusion
The molecule with the highest dipole moment is **Water (H₂O)** with a dipole moment of 1.84 D.

### Final Answer
Water (H₂O) has the highest dipole moment.

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