What is the frequency of X-rays of 10 nm wavelength? 6 x 1016 Hz 3 x 1016 Hz 3.00 Hz 6 x 108 Hz

The frequency of any wave is (wave speed) / (wavelength).

The speed of light is 3 x 10⁸ m/s.

If the wavelength is 10 nm (10⁻⁸ m), then the frequency is

(3 x 10⁸) / (10⁻⁸) = 3 x 10¹⁶ Hz

That's 30 million gigahertz!