Uranium is a metallic element that is used in nuclear reactors and nuclear weapons. The vast majority of uranium found on Earth is in the form of uranium-238, an isotope with a mass number of 238, while the uranium that is used for nuclear reactors and weapons is uranium-235, an isotope with a mass number of 235.
In a certain type of nuclear reactor, uranium-238 can be converted to plutonium-239, another radioactive element (with an atomic number of 94) that can be used to power nuclear reactions. Which of the following statements regarding uranium-238 and plutonium-239 is false?
An atom of plutonium-239 contains 145 neutrons.
An atom of plutonium-239 contains two more protons and one fewer neutron than an atom of uranium-238.
An atom of uranium-238 has a smaller mass than an atom of plutonium-239.
An atom of plutonium-239 contains one more proton than an atom of uranium-238.