Isotopes are defined as the chemical species of the same element which differs in the number of neutrons. The isotopes which are unstable are known as radioactive isotope. A radioactive (unstable )isotope can undergo 3 decay process:
1. Alpha Decay: In this decay process, a larger nuclei decays into smaller nuclei by releasing alpha particle. The particle released has a charge of +2 and a mass of 4 units.
2. Beta-minus decay: In this decay process, a neutron gets converted into a proton and an electron. the particle released during this process is a beta-particle.
3. Beta-plus decay: In this decay process, a protons gets converted into a neutron and electron-neutrino particle. The particle released during this process is a positron particle.
Isotopes which are unstable in nature can undergo these 3 decay processes.
All of the other options are ways that could help the environment from the chemicals, but if they just continue to use the chemicals then it would hurt the environment