Earthquakes with a richter magnitude of less than are generally not felt by humans.

The answer to this would be a magnitude of 2.5 or less. They usually are not felt nor do they cause damage, but they can be picked up by a seismograph.

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass

This is the most closely resembles the model.