Units of Radioactivity

There are two units of radioactivity and they are:

• Curie (Ci): If the radioactive substance decay at the rate of 3.7×10¹⁰ decays per second, then the unit used is Curie.
• Rutherford (rd): If the radioactive substance decay at the rate of 10⁶ decays per second, then the unit is Rutherford.