What is the SI unit for activity, defined as one decay per second?

1. Activity needs a standard SI unit to be compared across different samples. 2. That unit is the becquerel, defined as one decay per second. 3. The curie is a separate, non-SI unit historically tied to the activity of 1 g of radium-226. 4. The rem and rad describe radiation dose to tissue, not decay rate. 5. So the becquerel is correct. _Source: OpenStax Physics (CC BY 4.0), Ch 22 "The Atom", section 22.3 Half Life and Radiometric Dating_