Answer: The Nucleus: The Center of an Atom. The nucleus, that dense central core of the atom, contains both protons and neutrons. Electrons are outside the nucleus in energy levels. Protons have a positive charge, neutrons have no charge, and electrons have a negative charge.
A. Sedimentary rock. This is because sedimentary rock contains sediments and sometimes some fossils.
The most distant planet is pluto
it states that the atom is neutral, meaning the number of electrons and protons are the same. so if there are 13 electrons, there are 13 protons. And the mass number is neutrons plus protons. So 13+15 is 28