Chapter 7 - Electronic Structure - Questions and Exercises - Exercises - Page 285: 7.22

$1.22\times10^{-1}$ m , microwave region.

ν = $2.45\times10^{9}s^{-1}$ c = $2.997925\times10^{8}ms^{-1}$ λ = c/ν = $\frac{2.997925\times10^{8}ms^{-1}}{2.45\times10^{9}Hz}$ = $1.22\times10^{-1}m$. Refer Figure 7.4 to find the name of the spectral region.