Well hydrogen would be the main element, as a process called nuclear fusion with both helium and hydrogen atoms occurs within stars. And planets are the products of dead stars that have burned through their supplies of hydrogen, helium, and carbon. Planets are a product of this.
Answer:
The frequency , speed and wavelength of an electromagnetic wave are related by the formula
Speed = frequency x wavelength
frequency = speed / wavelength
substituting the values
frequency = 3 x #10 ^8# m /s / 1 x #10^15# m
= 3 x #10^-7# /s