Q.

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]

1 4  
2 2  
3 1  
4 3  

Ans.

(4)

E=13.6Z2[1n121n22]

13.6Z2[1119]=108.8

13.6×89(Z2)=108.8  Z=3