Number of moles of N₂ = 28g / 28 g/mol = 1 mole. Temperature change ΔT = 100°C = 100 K. Enthalpy change ΔH = nCₚΔT = 1 mol * 7 J K⁻¹ mol⁻¹ * 100 K = 700 J. (Note: The provided answer key seems to be based on 2 moles of N₂)