Answer:
2. have no negative particle
Explanation:
Helium atoms contains 2 neutrons and 2 protons (or 2 electrons). Thus, it has a mass number of 4 and atomic number of 2.
Alpha particles are heavy and positively charged, which make them to be deflected in a magnetic or electric charge. So, the helium atoms used as alpha particles for the gold foil experiment must have no negative particle.
