the ratio nof the maximum and minimum wavelengths in Brackets series of hydrozen spectra is

Options

A. `25/9`
B. `17/6`
C. `9/5`
D. `4/3`

Answer

A

Explanation

Brackets series of hydrogen spestrum is given by,
`1/lambda=R(1/4^2-1/n^2) `
for `n=5,6,7……`
For maximum wavelength, n=5
`1/lamda_max=R(1/4^2-1/5^2)R(1/16-1/25)=(9R)/400`
`lambda_max=400/(9R)`
For minimum wavelength ,`n=oo`
`1/lambda_min=R(1/2^2-1/oo^2)=R(1/16)=R/16`
`implies lambda_max/lambda_min=(9R)/((16)/R)=400/9xx1/6`
`25/9`