Calculate the energy required to excite one litre of hydrogen gas at 1 atm press

First, calculate moles of H2 in 1 L at 1 atm and 298 K: n = PV/RT = (1 × 1)/(0.0821 × 298) ≈ 0.0409 mol. This yields 0.0818 mol of H atoms after dissociation. The energy to excite one H atom from ground state (n=1) to first excited state (n=2) is 10.2 eV, which is 984 kJ/mol. Thus, excitation energy for all H atoms = 0.0818 mol × 984 kJ/mol ≈ 80.5 kJ. The dissociation energy (436 kJ/mol H2) adds about 17.8 kJ, giving a total of ~98.3 kJ, but the options only include the excitation portion. Option C (80.36 kJ) matches the excitation energy, so it is the best choice.