What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition `n=4` to `n=2` of `He^(+)` spectrum ?

Options

A. n = 4 to n = 1
B. n = 3 to n = 2
C. n = 3 to n = 1
D. n = 2 to n = 1

Answer

D

Explanation

For Balmer transition n = 14 to n = 2 in `He^(+)` spectrum.
`bar(nu) = (1)/(lambda) = R[(1)/(2^(2))-(1)/(4^(2))] xx 2^(2) = (3)/(4)R`
In H-spectrum for the same `bar(nu)` or `lambda` as
`Z = 1, n_(1) = 1, n_(2) = 2`