Question

an alpha particle is made up of ______. (1 point)
two electrons
one electron
one proton and one neutron
two protons and two neutrons

Explanation:

Alpha particles are helium - 4 nuclei. The atomic number of helium is 2 (number of protons), and the mass number is 4. Since mass number = number of protons + number of neutrons, the number of neutrons is \(4 - 2=2\). So, an alpha particle has two protons and two neutrons. Electrons are not part of alpha particles (alpha particles are positively charged due to protons and have no electrons as they are like bare nuclei). One proton and one neutron would be a deuteron (not an alpha particle).

Answer:

two protons and two neutrons