Answer
$5.8\times10^{18}Hz$
Work Step by Step
Wavelength (λ) =0.052 nm = $0.052\times10^{-9}m$
Speed (c) = $2.997925\times10^{8}ms^{-1}$
Frequency (ν)= $\frac{c}{λ} = \frac{2.997925\times10^{8}ms^{-1}}{0.052\times10^{-9}m}$ = $5.8\times10^{18}Hz$