Molecule which contains only sigma bonds in it is

Options

A. Pentene
B. Pentane
C. Pentadiene
D. Pentyne

Explanation

To determine which molecule contains only sigma bonds, we will analyze the given options: pentene, pentane, pentadiene, and pentyne.

### Step-by-Step Solution:

1. **Understand Sigma and Pi Bonds**:
- A sigma bond is formed by the head-on overlap of atomic orbitals and is present in all single bonds.
- A pi bond is formed by the side-to-side overlap of p orbitals and is present in double and triple bonds.

2. **Analyze Each Option**:
- **Pentene**:
- Pentene is an alkene with at least one double bond.
- Structure: C=C-C-C-C (double bond present) → Contains both sigma and pi bonds.
- **Conclusion**: Not only sigma bonds.

- **Pentane**:
- Pentane is an alkane with single bonds only.
- Structure: C-C-C-C-C (all single bonds) → Contains only sigma bonds.
- **Conclusion**: Contains only sigma bonds.

- **Pentadiene**:
- Pentadiene has two double bonds.
- Structure: C=C-C=C-C (two double bonds present) → Contains both sigma and pi bonds.
- **Conclusion**: Not only sigma bonds.

- **Pentyne**:
- Pentyne is an alkyne with at least one triple bond.
- Structure: C≡C-C-C-C (triple bond present) → Contains sigma and pi bonds.
- **Conclusion**: Not only sigma bonds.

3. **Final Conclusion**:
- The only molecule that contains only sigma bonds is **pentane**.

### Answer: Pentane contains only sigma bonds.

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