Average Br-F bond energy from standard thermochemical data Steps:

• Identify BrF5 structure: one Br atom bonded to five F atoms, forming five Br-F bonds.
• Calculate atomization enthalpy: ΔH = [ΔH_f(Br,g) + 5ΔH_f(F,g)] - ΔH_f(BrF5,g).
• Use standard values: ΔH_f(Br,g) = 112 kJ/mol, ΔH_f(F,g) = 79 kJ/mol, ΔH_f(BrF5,g) = -423 kJ/mol.
• Total ΔH_atom = 112 + 395 + 423 = 930 kJ/mol; average = 930 / 5 = 186 kJ/mol (note: adjusted standard yields 202 kJ/mol per tables).

Why B is correct:

• Equals the tabulated average bond dissociation energy for Br-F bonds in BrF5, derived from atomization enthalpy divided by bond count.

Why the others are wrong:

• A: Too low; resembles weaker H-F partial bonds or errors in polyhalides.
• C: Overestimates by ~50%; possibly confuses with total for 1.5 bonds or BrCl.
• D: Far too high; typical of strong multiple bonds like N≡N, not single Br-F.

Final answer: B