An isotope of cesium is radioactive. It decays by emitting a β−\beta^-β−-particle.
What happens to the nucleus of a cesium atom during the emission of the β−\beta^-β−-particle?
It becomes the nucleus of a different isotope of cesium with fewer neutrons.
It becomes the nucleus of a different isotope of cesium 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.
120 exam-style questions on CIE IGCSE Physics 5.2.3a Radioactive decay. Each one has a worked solution and a mark scheme showing where the marks go.