A radioactive nucleus emits an α\alphaα-particle.
What happens to the nucleon number (mass number) of the nucleus?
It stays the same.
It decreases by 2.
It decreases by 4.
It increases by 2.
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.