An electromagnetic radiation has an energy of 13.2 keV. Then the radiation belongs to the region of

X-ray

Energy of a photon $E = \frac{hc}{λ}$

$∴ \, wavelength \, λ=\frac{hc}{E}$

$=\frac{6.6×10^{-34}×3×10^8}{13.2×10^3×1.6×10^{-19}}$

$= 0.9375 × 10^{-10} \, m$

$ = 1 \, Å$

Wavelength range of X-rays is from 10^-11 m to 10^-8 m (0.1 Å to 100 Å).

Therefore, the given electromagnetic radiation belongs to the X-ray region of electromagnetic spectrum.