The frequency of an electromagnetic wave is related to its wavelength by the following equation:
frequency (f) = speed of light (c) / wavelength (λ)
Since the speed of light is approximately 3 x 10^8 m/s, and the wavelength of the ultraviolet wave in question is 350 nm, or 3.50 x 10^-7 m, we can plug these values into the equation to find the frequency:
f = 3 x 10^8 m/s / 3.50 x 10^-7 m
This simplifies to:
f = 8.57 x 10^14 Hz
Therefore, the correct answer is 8.6 x 10^14 Hz, letter B.