Blue-green light has a frequency of about 6x10to the 14 Hz.  Use the
relationship c=ft to find the wavelength of this light in air.  How
does this wavelength compare with the size of an atom, which is about
10 to the -10m?

Dear Daisy,

First off, a Hertz is one cycle per second (1/sec).

c = f T
The speed of light = frequency times Time (period of the wave).

c = 3.0 * 10^8 m/s is the speed of light.
f = 6*10^14 Hz is the frequency of the blue-green light.
You don't define the term t, which usually means time, but in this
context it must be the wavelength.

First, solve the equation above for the unknown we want to find (wavelength)

T = c / f
  = (3*10^8 m/s ) / (6*10^14/s)
  = 0.5 * 10^-6 m
T  = 5 * 10^-7 m (or 0.5 micrometers or 500 nanometers)

Compared to the size of the atom this is
5*10^-7m / 10^-10m = 0.5 * 10^3 = 5 * 10^2 = 500

So, the wavelength of the blue-green light is about 500 times greater
than the size of an atom.

Here are some useful links about the physics of light:
http://www.glenbrook.k12.il.us/gbssci/phys/Class/light/u12l2a.html
http://www.purchon.com/physics/electromagnetic.htm
http://directory.google.com/Top/Kids_and_Teens/School_Time/Science/Physics/Light_and_Optics/

I hope this answer was helpful.

           -welte-ga