∴∴​ΔE2−1​=13.6×Z2[1−41​]=13.6×Z2[43​]ΔE3−2​=13.6×Z2[41​−91​]=13.6×Z2[365​]ΔE2​=ΔE3−2​+74.813.6×Z2[43​]=13.6×Z2[365​]+74.813.6×Z2[43​−365​]=74.8Z2=9Z=3​