The bond length between central carbon atom and other carbon atom is minimum in

Options

A. Propene
B. Propyne
C. Propane
D. pentane

Answer

To determine which molecule has the minimum bond length between the central carbon atom and another carbon atom, we need to analyze the bond types present in the given hydrocarbons: propene, propyne, propane, and pentane.

### Step-by-Step Solution:

1. **Identify the Molecules**:
- **Propene (C3H6)**: Contains a double bond between two carbon atoms.
- **Propyne (C3H4)**: Contains a triple bond between two carbon atoms.
- **Propane (C3H8)**: Contains only single bonds between carbon atoms.
- **Pentane (C5H12)**: Contains only single bonds between carbon atoms.

2. **Determine the Bond Order**:
- **Propene**: The bond order between the central carbon and the adjacent carbon is 2 (double bond).
- **Propyne**: The bond order between the central carbon and the adjacent carbon is 3 (triple bond).
- **Propane**: The bond order between the central carbon and the adjacent carbon is 1 (single bond).
- **Pentane**: The bond order between the central carbon and the adjacent carbon is also 1 (single bond).

3. **Understand the Relationship Between Bond Order and Bond Length**:
- Bond length is inversely proportional to bond order. This means that as the bond order increases, the bond length decreases.
- Therefore, a triple bond (bond order of 3) will have a shorter bond length than a double bond (bond order of 2), which in turn will have a shorter bond length than a single bond (bond order of 1).

4. **Compare the Bond Lengths**:
- **Propyne** has the highest bond order (3), which means it has the shortest bond length.
- **Propene** has a bond order of 2, resulting in a longer bond length than propyne but shorter than propane and pentane.
- **Propane and Pentane** both have a bond order of 1, resulting in the longest bond lengths among the options.

5. **Conclusion**:
- The bond length between the central carbon atom and the other carbon atom is minimum in **Propyne** (option B).

### Final Answer:
The bond length between the central carbon atom and another carbon atom is minimum in **Propyne**.