To answer part a of this question, you need to know that the wavelength and frequency are related using the equation:
speed of light = frequency x wavelength
You should also know that as the wavelength increases, the frequency decreases. So radiation with shorter wavelengths has higher frequency and is generally more damaging to tissue.
All electromagnetic radiation travels at the same speed, 3.0 x 10^8 m/s. So to solve this problem, substitute:
3.0 x 10^8 m/s = (3.2 x 10^5 m) x frequency
So the frequency is 9.4 x 10^2 1/s or Hz (Hertz).
To answer part b you need to consult the electromagnetic spectrum (see below). Locate the region of the EMS that matches either the wavelength or frequency. This is in the long radio waves section. Hope this helps!