The molecules having dipole moment are :

Options

A. 2,2-Dimethylpropane
B. trans-Pent-2-ene
C. cis-Hex-3-ene
D. 2,2,3,3-Tetramethylbutane

Explanation

To determine which molecules have dipole moments, we need to analyze the molecular structures and the arrangement of their bonds. A dipole moment arises in a molecule when there is an uneven distribution of electron density, typically due to differences in electronegativity between atoms. Here’s a step-by-step breakdown of the given question:

### Step 1: Analyze 2,2-Dimethylpropane
1. **Structure Drawing**: 2,2-Dimethylpropane has a three-carbon chain (propane) with two methyl groups attached to the second carbon.
- Structure:
```
CH3
|
CH3 - C - CH3
|
CH3
```
2. **Dipole Moment Analysis**: The dipole moments from the methyl groups will cancel each other out because they are symmetrically placed around the central carbon atom.
3. **Conclusion**: The dipole moment for 2,2-dimethylpropane is zero.

### Step 2: Analyze Trans-Pent-2-ene
1. **Structure Drawing**: Trans-pent-2-ene has a double bond between the second and third carbon atoms, with a methyl group on one side and an ethyl group on the other.
- Structure:
```
CH3 - C = C - CH2 - CH3
```
2. **Dipole Moment Analysis**: The methyl and ethyl groups create a dipole moment that does not cancel out because they have different electronegativities.
3. **Conclusion**: Trans-pent-2-ene has a net dipole moment.

### Step 3: Analyze Cis-Hex-3-ene
1. **Structure Drawing**: Cis-hex-3-ene has a double bond between the third and fourth carbon atoms, with both methyl and ethyl groups on the same side of the double bond.
- Structure:
```
CH3 - CH = CH - CH2 - CH3
```
2. **Dipole Moment Analysis**: The dipole moments from the methyl and ethyl groups do not cancel out due to their different sizes and electronegativities.
3. **Conclusion**: Cis-hex-3-ene has a net dipole moment.

### Step 4: Analyze 2,2,3,3-Tetramethylbutane
1. **Structure Drawing**: 2,2,3,3-Tetramethylbutane has a four-carbon chain with two methyl groups on the second carbon and two on the third.
- Structure:
```
CH3
|
CH3 - C - C - CH3
| |
CH3 CH3
```
2. **Dipole Moment Analysis**: The symmetrical arrangement of the methyl groups means that all dipole moments will cancel out.
3. **Conclusion**: The dipole moment for 2,2,3,3-tetramethylbutane is zero.

### Final Conclusion
From the analysis:
- **Molecules with dipole moments**: Trans-pent-2-ene and Cis-hex-3-ene.
- **Molecules without dipole moments**: 2,2-dimethylpropane and 2,2,3,3-tetramethylbutane.

### Answer:
The molecules having dipole moments are **Trans-pent-2-ene and Cis-hex-3-ene**.

---