Frequency is how we explain how often a process .....?

What is used to describe the motion of waves and states how often a complete cycle of the wave motion  goes through in a given time? 

The unit of frequency is measured in Hertz which was named after a guy called ......?

moves sound

frequency

Hans Hertz

changes tone

waves

Heinrich Hertz

repeats it self

motion

Helmut Hertz

In what year did Hertz begin working on electromagnetic radiation?