text: In physics, the<unk>  is a subatomic particle with no net electric charge and a mass of 939.573 MeV/c² or 1.008 664 915 (78) u (1.6749 × 10−27 kg, slightly more than a proton). Its spin is ½. Its antiparticle is called the antineutron. The<unk> , along with the proton, is a nucleon.
  The nuclei of all atoms consist of protons and<unk> s, except the lightest isotope of hydrogen which has only a single proton. The number of protons defines the type of element the atom forms. The number of<unk> s determines the isotope of an element, therefore isotopes are atoms of the same element (i.e. atomic number) but differing atomic masses due to a different number of<unk> s. For example, the carbon-12 isotope has 6 protons and 6<unk> s, while the carbon-14 isotope has 6 protons and 8<unk> s.
  A<unk>  consists of two down quarks and one up quark.  Since it has three quarks, it is classified as a baryon.
option_0: Neutron
option_1: Electron
option_2: Activated carbon
option_3: Carbon black
option_4: Wart
option_5: Colloid
option_6: Syngas
option_7: Carbon suboxide