Question

Which of the following pair of molecules contain odd electron molecule and an expanded octet molecule?

• A. BCl₃ and SF₆
• B. NO and H₂SO₄
• C. SF₆ and H₂SO₄
• D. BCl₃ and NO

Answer 1

The Correct Option is B

To correctly answer the question, we need to identify which pair of molecules features one molecule with an odd electron and another molecule with an expanded octet.

Definitions:

• Odd Electron Molecule: These are molecules with an unpaired electron, resulting in a radical. An example of this is nitric oxide (NO), which has one unpaired electron.
• Expanded Octet Molecule: Some molecules have atoms that hold more than 8 electrons in their valence shell, often seen in elements from period 3 or below. Sulfur hexafluoride (SF₆) is an example where sulfur has 12 electrons in its valence shell.

Analyzing the Options:

1. BCl₃ and SF₆:
   • BCl₃: Boron trichloride has incomplete octets and no unpaired electrons.
   • SF₆: Sulfur in SF₆ has an expanded octet (12 electrons).
   • The pair has one expanded octet molecule but not an odd electron molecule.
2. NO and H₂SO₄:
   • NO: Nitric oxide has an unpaired electron, making it an odd electron molecule.
   • H₂SO₄: Has sulfate ion (SO₄^2-) where sulfur uses an expanded octet as it shares more than 8 electrons.
   • This pair contains one odd electron molecule and one expanded octet molecule. Therefore, it is the correct answer.
3. SF₆ and H₂SO₄:
   • Both SF₆ and H₂SO₄ have expanded octets but neither has odd electrons.
4. BCl₃ and NO:
   • BCl₃: Again, has incomplete octets with no unpaired electrons.
   • NO: Has an unpaired electron, so it is an odd electron molecule.
   • The pair has one odd electron molecule, but not an expanded octet molecule.

Conclusion: The correct pair is NO and H₂SO₄ as this pair correctly fulfills the criteria of one odd electron and one expanded octet molecule.