1.

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

Answer»

`(4)/(3)`
`(525)/(376)`
25
`(900)/(11)`

Solution :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)`


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