To determine which of the given pairs of molecules contains one molecule with an odd electron and another with an expanded octet, we need to analyze the electron configurations and bonding structures of each pair: Option A: BeCl2&HNO3 BeCl2 : Beryllium chloride has a linear structure and does not have an odd electron. HNO3 : Nitric acid does not have an odd electron nor an expanded octet. The nitrogen in HNO3 obeys the octet rule. Option B: NO&PF5 NO: Nitric oxide has an odd electron (one unpaired electron). PF5 : Phosphorus pentafluoride has an expanded octet (10 electrons around phosphorus). Option D: SCl2&NH3 SCl2 : Sulfur dichloride has no odd electron and typically does not have an expanded octet. NH3 : Ammonia has no odd electron and does not exhibit an expanded octet. Therefore, the correct answer is: Option B: NO&PF5