Radioactive Substances and Emissions

Radioactive substances are materials that contain unstable atomic nuclei, which means they undergo spontaneous decay and emit ionizing radiation. This radiation can take various forms, including alpha particles, beta particles, gamma rays, and electromagnetic radiation.

Explanation of the Correct Answer

Option 'D' states that neutrons are not emitted by radioactive substances. This answer is correct because neutrons are not considered a form of radiation emitted by radioactive materials. Neutrons are subatomic particles found in the nucleus of an atom, and they do not have an electrical charge.

Other Options Explained

a) Electrons: Electrons are negatively charged particles that are emitted during the radioactive decay of certain isotopes. This process is called beta decay, and it involves the conversion of a neutron into a proton. As a result, an electron is emitted from the nucleus.

b) Electromagnetic Radiations: Electromagnetic radiation includes various types of energy waves, such as gamma rays, X-rays, ultraviolet rays, visible light, infrared rays, microwaves, and radio waves. Gamma rays are a type of electromagnetic radiation that is emitted by radioactive substances during the decay process.

c) Alpha Particles: Alpha particles are composed of two protons and two neutrons, making them identical to the helium nucleus. They are emitted during alpha decay, which occurs when an unstable nucleus releases an alpha particle to become more stable. Alpha particles have a positive charge and are relatively large compared to other subatomic particles.

Conclusion

In summary, neutrons are not emitted by radioactive substances. While electrons, electromagnetic radiation, and alpha particles are all forms of radiation emitted during radioactive decay, neutrons themselves are not considered a form of radiation.