Ratio of shortest wavelength of Balmer series in a hydrogen atom to that of Lymann series in a He+ ion is
1 : 4
8 : 1
1 : 8
16 : 1
for any series shortest wavelength can be given by 1λ=RZ21n2-1∞ where R is the Rydberg's constant and Z is the atomic no.
For Balmer series in hydrogen atom 1λ1=R122−1∝=R4
For Lymann series of He+ is 1λ2=4R112-1∞
∴ λ1λ2=4/R1/4R=16