The ratio of longest wavelength and the shortest wavelength observed in the 5 spectral series of emission spectrum of hydrogen is .......

Options

A. `(4)/(3)`
B. `(525)/(376)`
C. 25
D. `(900)/(11)`

Answer

D

Explanation

When the wavelength of first line of Pfund series is maximum for that
`"ln" (1)/(lambda)=R[(1)/(m^(2))-(1)/(n^(2))], m=5 and n=6`
`:. (1)/(lambda_(F))=R[(1)/(5^(2))-(1)/(6^(2))]`
`:. (1)/(lambda_(F))=(11R)/(900)`
`:. (1)/(lambda_(F))=(900)/(11R)...(1)`
For shortest wavelength in Lyman series m=1 and `n=oo`
`:. (1)/(lambda_(L))=R[(1)/(1^(2))-(1)/(oo^(2))]=(R)/(1)`
` :. (1)/(lambda_(L))=(1)/(R) ...(2)`
`rArr` Ratio `=(lambda_(F))/(lamda_(L))=(900)/(11R)xx(R)/(1)=(900)/(11)`