A researcher is using a particle accelerator in an experiment studying isotopes. How can the researcher change one isotope into a different isotope of the same element?

by removing valence electrons

by adding valence electrons

by adding or removing protons

by adding or removing neutrons

The researcher can change one isotope into a different isotope of the same element by adding or removing neutrons. This is because, isotopes are two or more forms of an element which contain equal number of protons and electrons but different number of neutrons. Isotopes differ in relative atomic mass but have same chemical properties.