I believe C is the answer <span />
The nucleus of an atom is made up of Protons and Neutrons.
Hope this answers your question :) ~
Group 18 is known as the Noble/ Inert Gases
Frequency is defined as the number of waves per second. In this machine 25 waves pass in one second.
We need to calculate the number of waves that pass a particular point during one second.
During 2 seconds -25 waves
Therefore in one second - 25/2 = 12.5 waves/s.
1 wave per second has the unit Hertz (Hz)
Therefore answer is 12.5 Hz
