Quantum Theory and Wave–Particle Duality Practice Test

In a Compton scattering experiment, X-rays of known wavelength scatter from electrons, and the scattered wavelength increases with scattering angle. Classical wave scattering cannot explain a wavelength change that depends on angle and target electrons. Which statement best explains the shift?

X-rays scatter from a graphite target and show a shift in wavelength that depends on scattering angle. Classical wave theory cannot explain a wavelength change from scattering off free electrons. Which statement best explains what this indicates about electromagnetic radiation?