An isotope of radon is radioactive. It decays by emitting an α-particle. What happens to the nucleus of a radon atom during the emission of the α-particle?
It becomes the nucleus of a different isotope of radon with fewer neutrons.
It becomes the nucleus of a different isotope of radon with more neutrons.
It becomes the nucleus of an element with a higher proton number.
It becomes the nucleus of an element with a lower proton number.
