Correct sequence of bond length is:

Options

A. `HC -= CH gt H_2 C = CH_2 gt H_3 C - CH_3`
B. `H_2 C = CH_2 gt HC -= CH gt H_3 C - CH_3`
C. `H_3 C - CH_3 gt H_2 C = CH_2 gt HC -= CH`
D. `H_3 C - CH_3 gt HC -= HC gt H_2 C = CH_2`

Answer

To determine the correct sequence of bond lengths based on bond order, we can follow these steps:

### Step 1: Understand Bond Length and Bond Order
- **Bond Length**: The distance between the nuclei of two bonded atoms.
- **Bond Order**: The number of bonds between two atoms. A single bond has a bond order of 1, a double bond has a bond order of 2, and a triple bond has a bond order of 3.

### Step 2: Relationship Between Bond Order and Bond Length
- The bond length is inversely proportional to the bond order. This means:
- Higher bond order → Shorter bond length
- Lower bond order → Longer bond length

### Step 3: Analyze Different Types of Bonds
- **Single Bond (Bond Order = 1)**: This bond has the longest bond length because it involves only one bond between the two atoms.
- **Double Bond (Bond Order = 2)**: This bond is shorter than a single bond due to the presence of two bonds pulling the atoms closer together.
- **Triple Bond (Bond Order = 3)**: This bond has the shortest bond length because three bonds pull the atoms even closer than a double bond.

### Step 4: Sequence the Bonds by Length
- Based on the bond order:
- **Single Bond** (Longest)
- **Double Bond** (Intermediate)
- **Triple Bond** (Shortest)

### Conclusion
The correct sequence of bond lengths from longest to shortest is:
1. Single Bond
2. Double Bond
3. Triple Bond

### Final Answer
The correct sequence of bond lengths is: **Single Bond > Double Bond > Triple Bond**.

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