Dipole moment of `CH_(3)CH_(2)CH_(3)(I),CH_(3)CH_(2)OH(II)` and `CH_(3)CH_(2)F(III)` is in order

Options

A. `IltIIltIII`
B. `IgtIIgtIII`
C. `IltIIIltII`
D. `IIIltIltII`

Answer

To determine the order of dipole moments for the compounds \( CH_3CH_2CH_3 \) (I), \( CH_3CH_2OH \) (II), and \( CH_3CH_2F \) (III), we can analyze the molecular structures and the electronegativities of the atoms involved.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- Compound I: \( CH_3CH_2CH_3 \) (Propane)
- Compound II: \( CH_3CH_2OH \) (Ethanol)
- Compound III: \( CH_3CH_2F \) (Ethyl fluoride)

2. **Understand Dipole Moment**:
- The dipole moment (\( \mu \)) is a measure of the separation of positive and negative charges in a molecule. It is defined as:
\[ \mu = Q \times D \]
where \( Q \) is the charge and \( D \) is the distance between the charges.

3. **Electronegativity Consideration**:
- Electronegativity is the tendency of an atom to attract electrons. The electronegativities of the relevant atoms are:
- Carbon (C): 2.5
- Oxygen (O): 3.5
- Fluorine (F): 4.0
- Therefore, the order of electronegativity is: \( F > O > C \).

4. **Analyze Each Compound**:
- **Compound I: \( CH_3CH_2CH_3 \)** (Propane)
- This compound is non-polar because it consists only of carbon and hydrogen atoms, which have similar electronegativities. Thus, it has a very low dipole moment (close to 0).
- **Compound II: \( CH_3CH_2OH \)** (Ethanol)
- Ethanol has a hydroxyl (-OH) group, which is polar due to the electronegativity of oxygen. This gives ethanol a significant dipole moment.
- **Compound III: \( CH_3CH_2F \)** (Ethyl fluoride)
- Ethyl fluoride has a fluorine atom, which is highly electronegative. This creates a strong dipole moment due to the significant difference in electronegativity between carbon and fluorine.

5. **Order of Dipole Moments**:
- Based on the analysis:
- \( CH_3CH_2CH_3 \) has the lowest dipole moment (I).
- \( CH_3CH_2OH \) has a moderate dipole moment (II).
- \( CH_3CH_2F \) has the highest dipole moment (III).
- Therefore, the order of dipole moments is:
\[ \mu (I) < \mu (II) < \mu (III) \]

### Final Answer:
The order of dipole moments is \( CH_3CH_2CH_3 < CH_3CH_2OH < CH_3CH_2F \).