*What are the three types of radiation?
*Describe how a substance becomes radioactive?
-An unstable nucleus becomes stable or less unstable by emitting alpha, beta or gamma radiation.
*What is an isotope?
-Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.
*What it's background radiation?
Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate introduction of radiation sources.