Which of the following will show least dipole character ?

Options

A. Water
B. Ethnol
C. Ethane
D. Ether

Answer

To determine which of the given compounds shows the least dipole character, we will analyze the dipole moments of each compound step by step.

### Step 1: Analyze Water (H₂O)
- **Structure**: Water has a bent structure due to two lone pairs on the oxygen atom.
- **Electronegativity**: Oxygen (3.5) is more electronegative than hydrogen (2.2).
- **Dipole Moment**: The dipole moment in water is directed towards the oxygen atom, resulting in a net dipole moment of approximately 1.85 D (Debye).

### Step 2: Analyze Ethanol (C₂H₅OH)
- **Structure**: Ethanol has a hydroxyl (-OH) group attached to an ethyl group (C₂H₅).
- **Electronegativity**: The electronegativity of carbon is 2.55 and oxygen is 3.5. The C-O bond is polar due to the difference in electronegativity.
- **Dipole Moment**: The dipole moment in ethanol is approximately 1.69 D, which is lower than that of water but still significant.

### Step 3: Analyze Ethane (C₂H₆)
- **Structure**: Ethane consists of two carbon atoms bonded to each other and to hydrogen atoms.
- **Electronegativity**: The electronegativity difference between carbon and hydrogen is minimal (C: 2.55, H: 2.2), leading to non-polar C-H bonds.
- **Dipole Moment**: Ethane has a dipole moment of approximately 0 D, indicating it is a non-polar molecule.

### Step 4: Analyze Dimethyl Ether (C₂H₆O)
- **Structure**: Dimethyl ether has the structure CH₃-O-CH₃.
- **Electronegativity**: The C-O bond is polar due to the electronegativity difference, but the molecule has symmetrical geometry.
- **Dipole Moment**: The dipole moment is present but is less significant compared to water and ethanol. However, it is not zero.

### Conclusion
After analyzing the dipole moments of all compounds:
- Water (H₂O) has a dipole moment of 1.85 D.
- Ethanol (C₂H₅OH) has a dipole moment of 1.69 D.
- Dimethyl ether (CH₃-O-CH₃) has a dipole moment that is not zero but less than that of water and ethanol.
- Ethane (C₂H₆) has a dipole moment of 0 D.

Thus, the compound with the least dipole character is **Ethane (C₂H₆)**.