Which of the following is the correct sequence of the bond length?

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 among different types of carbon bonds (single, double, and triple), we need to understand the relationship between bond order and bond length.

### Step-by-Step Solution:

1. **Understanding Bond Length**:
- Bond length is the distance between the nuclei of two bonded atoms. It is influenced by the type of bond formed between them (single, double, or triple).

2. **Bond Order Concept**:
- Bond order refers to the number of bonds between two atoms. For example:
- A single bond has a bond order of 1.
- A double bond has a bond order of 2.
- A triple bond has a bond order of 3.

3. **Relationship Between Bond Order and Bond Length**:
- There is an inverse relationship between bond order and bond length:
- Higher bond order means shorter bond length.
- Lower bond order means longer bond length.
- This is because as the number of bonds increases, the atoms are pulled closer together, resulting in a shorter bond length.

4. **Comparing Carbon Bonds**:
- For carbon:
- Carbon-carbon single bond (C-C): Bond order = 1 (longest bond length)
- Carbon-carbon double bond (C=C): Bond order = 2 (intermediate bond length)
- Carbon-carbon triple bond (C≡C): Bond order = 3 (shortest bond length)

5. **Sequence of Bond Lengths**:
- Based on the bond orders:
- Single bond (C-C) has the longest bond length.
- Double bond (C=C) has a shorter bond length than the single bond.
- Triple bond (C≡C) has the shortest bond length.
- Therefore, the correct sequence of bond lengths from longest to shortest is:
- C-C > C=C > C≡C

6. **Final Answer**:
- The correct sequence of bond lengths is: **C-C > C=C > C≡C**.