In a hydrogen like ion, the energy difference between the 2nd excitation energy state and ground is 108.8 eV. The atomic number of the ion is [2025]
(4)
△E=13.6Z2[1n12–1n22]
13.6Z2[11–19]=108.8
13.6×89(Z2)=108.8 ⇒ Z=3