Q.

The shortest wavelength of hydrogen atom in Lyman series is λ. The longest wavelength in Balmer series of He+ is              [2023]

1 9λ5  
2 36λ5  
3 5λ9  
4 59λ  

Ans.

(1)

(1) For Hydrogen atom (Z=1):

       (1λ)H=RH(1)2[112-12]Last line

(2) For He+ atom (Z=2):

      (1λ)He+=RH(2)2[122-132]=RH[1-49]

      =RH(59)first line

       From (1) and (2)

λHe+λH=95

λHe+=9λH5