The transitionis `He^(o+)` ion that would have the same wavelength as the first Lyman line in hydtrogen spectrum is

Options

A. `2 rarr 1`
B. `5 rarr 3`
C. `4 rarr 2`
D. `6 rarr 4`

Answer

C

Explanation

`bar v _(He^(o+)) = (1)/(lambda) = R xx 2^(2) ((1)/(n_(1)^(2))- (1)/(n_(2)^(2)))`
`= R ((4)/(n_(1)^(2)) - (4)/(n_(2)^(2)))`…..(i)
`bar v _(theta_(2)^(o+)) = (1)/(lambda) = R xx ((1)/(1^(2))- (1)/(2^(2)))`….(ii)
Compare equation (i) and (ii) we get
`(1)/(1^(2)) = (4)/(n_(1)^(2)), n_(1)^(2)= 4 n_(1) = 2`
`(4)/(n_(2)^(2)) = (1)/(2^(2)),n_(2)^(2)= 16 n_(2) = 4`
`( h rarr 2)`