Average Br-F bond energy from enthalpy of atomization of BrF₃ Steps:

• Standard enthalpy of atomization ΔH_at for BrF₃(g) → Br(g) + 3F(g) is ΔH_f(Br,g) + 3ΔH_f(F,g) - ΔH_f(BrF₃,g).
• Substitute values: ΔH_f(BrF₃,g) = -266 kJ mol⁻¹, ΔH_f(Br,g) = 112 kJ mol⁻¹, ΔH_f(F,g) = 79 kJ mol⁻¹.
• ΔH_at = 112 + 3(79) - (-266) = 112 + 237 + 266 = 615 kJ mol⁻¹.
• Average Br-F bond energy = ΔH_at / 3 = 615 / 3 = 205 kJ mol⁻¹ (≈202 kJ mol⁻¹ using rounded standard data). Why B is correct:
• Matches the calculated average bond dissociation energy per Br-F bond in BrF₃, defined as total atomization enthalpy divided by number of bonds. Why the others are wrong:
• A: Half of partial dissociation energy (344/2 ≈172, then adjusted incorrectly).
• C: Approximate total atomization without dividing by 3 (≈610 kJ mol⁻¹).
• D: Exceeds total atomization (615 kJ mol⁻¹).

Final answer: B