To measure the strength of an earthquake, you can use either a Richter scale or Mercalli scale. Richter scale uses the amplitued of the wave and the distance from the source. Mercalli scale uses observations of people and is not considered to be scientific as Richter scale.
The vector sum of forces acting on a non-accelerating object equals zero.
equation form: ΣF = 0
It would be the first option.
Explanation-
The number of protons is equal to the atomic number the number of neutrons is the mass minus the atomic number.
