1.

The shoretest wavelength in Lyman series is 91.2 nm. The longest wavelength of the series isA. 121.6 nmB. 182.4 nmC. 243. 4nmD. 364.8 nm

Answer» Correct Answer - A
The wavelength `(lambda)` of lines is given by
`" " (1)/(lambda)=R((1)/(1^(2))-(1)/(n^(2)))`
For Lyman seris, the shortest wavelength is for `n=oo` and longest is for n=2
`:. " " (1)/(lambda_(s))=R((1)/(1^(2)))" "....(i)`
`" " (1)/(lambda_(L))=R((1)/(1^(2))-(1)/(2^(2)))=(3)/(4)R" "....(ii)`
On dividing Eq. (ii) by Eq. (ii), we get `" " (lambda_(L))/(lambda_(s))=(4)/(3)`
Given `" " lambda_(s)=91.2 nm rArr lambda_(L)=91.2xx(4)/(3)=121.6 nm`


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