1.

Hydrogen atom in ground state is excited by a monochromatic radiation of wavelength lambda = 975 Å then number of spectral lines in resulting spectrum emitted will be ......

Answer»

3
2
6
10

Solution :Energy of incident PHOTON,
`E=hf=(hC)/(lambda)`
`:.E=(6.625xx10^(-34)xx3xx10^(8))/(975xx10^(-10)xx1.6xx10^(-19))eV`
`0.012746xx10^(3)`
`=12.75eV`
Now `E=-(13.6)/(N^(2))-(-(13.6)/(1^(2)))`
`12.75=-(13.6)/(n^(2))+13.6`
`:.(13.6)/(n^(2))=13.6-12.75`
`:.(13.6)/(n^(2))=0.85eV`
`:.n^(2)=(13.6)/(0.85)=16`
`:. n=4`
`:.` No, of spectral lines,
`=(n(n-1))/(2)`
`=(4(4-1))/(2)`
`=6`


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