The extreme wavelength of Paschen series are

Options

A. `0.365 mu m` and `0.565 mu m`
B. `0.818 mu m` and `1.89 mu m`
C. `1.45 mu m` and `4.04 mu m`
D. `2.27 mu m` and `7.43 mu m`

Answer

B

Explanation

In Paschen series `(1)/(lambda_(max)) = R [(1)/((3)^(2)) - (1)/((4)^(2))]`
`rArr lambda_(max) = (144)/(7R) = (144)/(7 xx 1.1 xx 10^(7))`
`= 1.89 xx 10^(-6)m = 1.89 mu m`
Similarly `lambda_(min) = (9)/(R ) = (9)/(1.1 xx 10^(7)) = 0.818 mu m`