Which of the following compound has the lowest dipole moment

Options

A.
B. `CH_(3)C-=C CH_(3)`
C. `CH_(3)CH_(2)c-=CH`
D. `CH_(2)=CH-C-=CH`

Explanation

To determine which compound has the lowest dipole moment, we need to analyze the given compounds and their molecular structures. The dipole moment depends on the electronegativity of the atoms involved and the geometry of the molecule.

### Step-by-Step Solution:

1. **Understanding Dipole Moment**: The dipole moment is a vector quantity that represents the separation of positive and negative charges in a molecule. It is directed from the more electropositive atom to the more electronegative atom.

2. **Analyzing the Compounds**: We need to evaluate the dipole moments of the given compounds based on their structures and the hybridization of the carbon atoms involved.

3. **Compound 1**: Let's consider the first compound, which has sp² and sp³ hybridized carbons. The dipole moments will not cancel out completely due to the different electronegativities of the atoms involved. Thus, this compound will have a non-zero dipole moment.

4. **Compound 2**: The second compound is CH₃-C≡C-CH₃. Here, the dipole moments from the two CH₃ groups will cancel each other out because they are symmetrical and equal in magnitude. Therefore, the net dipole moment for this compound is zero.

5. **Compound 3**: The third compound is CH₃-CH₂-C≡C-H. In this case, the dipole moments do not cancel out completely due to the presence of hydrogen atoms and the different hybridizations (sp and sp³). Hence, this compound will have a non-zero dipole moment.

6. **Compound 4**: The fourth compound is CH₂=CH-C≡C-H. The dipole moments from the hydrogen atoms will not cancel out completely due to the different hybridizations (sp² and sp). Therefore, this compound also has a non-zero dipole moment.

7. **Conclusion**: Among the four compounds analyzed, the second compound (CH₃-C≡C-CH₃) has the lowest dipole moment, which is zero.

### Final Answer:
The compound with the lowest dipole moment is **CH₃-C≡C-CH₃** (Compound 2).