The correct order of electronegativity of carbon in ethane, ethene and ethyne is

Options

A. `"ethane" lt "ethene" lt "ethyne"`
B. `"ethyne" lt "ethene" lt "ethane"`
C. `"ethene" lt "ethyne" lt "ethane"`
D. `"ethene" lt "ethane" lt "ethyne"`

Answer

To determine the correct order of electronegativity of carbon in ethane (C2H6), ethene (C2H4), and ethyne (C2H2), we need to consider the hybridization and the corresponding s-character of the carbon atoms in each molecule.

### Step-by-Step Solution:

1. **Identify the Hybridization of Carbon in Each Compound:**
- **Ethane (C2H6):** The carbon atoms in ethane are sp³ hybridized. Each carbon is bonded to three hydrogens and one carbon, leading to a tetrahedral geometry.
- **Ethene (C2H4):** The carbon atoms in ethene are sp² hybridized. Each carbon is bonded to two hydrogens and one carbon, resulting in a trigonal planar structure.
- **Ethyne (C2H2):** The carbon atoms in ethyne are sp hybridized. Each carbon is bonded to one hydrogen and one carbon, giving a linear structure.

2. **Determine the s-Character:**
- **sp³ Hybridization (Ethane):** 25% s-character (75% p-character).
- **sp² Hybridization (Ethene):** 33.3% s-character (66.7% p-character).
- **sp Hybridization (Ethyne):** 50% s-character (50% p-character).

3. **Relate s-Character to Electronegativity:**
- Electronegativity increases with increasing s-character. This is because the s orbital is closer to the nucleus and holds the electrons more tightly.
- Therefore, the order of electronegativity based on s-character is:
- Ethyne (sp) > Ethene (sp²) > Ethane (sp³).

4. **Conclusion:**
- The correct order of electronegativity of carbon in ethane, ethene, and ethyne is:
- **Ethyne > Ethene > Ethane.**

### Final Answer:
The correct order of electronegativity of carbon in ethane, ethene, and ethyne is:
**Ethyne > Ethene > Ethane.**