The largest wavelength in the ultraviolet region of the hydrogen spectrum is 122 nm. The smallest wavelength in the infrared region of the hydrogen spectrum (to the nearest integer) is

Explanation

The smallest frequency and largest wavelength in ultraviolet region wil be for transition of electron from orbit 2 to orbit 1.
`:.1/(lamda)=R(1/(n_(1)^(2))-1/(n_(2)^(2)))`
`implies1/(122xx10^(-9)m)=R[1/(1^(2))-1/(2^(2))]=R[1-1/4]=(3R)/4`
`impliesR=4/(3xx122xx10^(-9))m^(-1)`
The highest frequency and smallest wavelength for infrared region will be for transition of electron from `oo` to 3rd orbit.
`:.1/(lamda)=R(1/(n_(1)^(2))-1/(n_(2)^(2)))`
`implies1/(lamda)=4/(3xx122xx10^(-9))(1/(3^(2))-1/(oo))`
`:.lamda=(3xx122xx9xx10^(-9))/4=823.5nm`