A cell phone sends signals at about 850 MHz (where 1 MHz = 1 × 10⁶ Hz or cycles per second). 

(a) What is the wavelength of this radiation? 

(b) What is the energy of 1.0 mol of photons with a frequency of 850 MHz?

(c) Compare the energy in part (b) with the energy of a mole of photons of violet light (420 nm).

(d) Comment on the difference in energy between 850 MHz radiation and violet light.