Respuesta :

Answer;

54 neutrons

Explanation;

  • Atomic number of an atom is the number of protons in its nucleus. Since protons are positively charged, it makes the nucleus to be positively charged.
  • A neutral atom has equal number of protons and electrons, thus the atomic number of a neutral atom is also equivalent to the number of electrons.
  • Mass number of an atom is the sum of protons and neutrons in the nucleus of the atom.
  • Therefore, to get the number of neutrons we subtract the atomic number from the mass number. That is; 78 -24 = 54 neutrons.