What unit measures the rate of disintegration of radioactive material?

The correct answer to the question about the unit that measures the rate of disintegration of radioactive material is the Becquerel. This unit is defined as one disintegration per second, which directly quantifies the activity of a radioactive sample. The Becquerel is a fundamental unit in the International System of Units (SI) used specifically for measuring radioactivity, reflecting how many atomic nuclei disintegrate in a given time frame.

On the other hand, Grays and Sieverts are units that measure absorbed dose and biological effect respectively, rather than the rate of radioactive decay. The Gray quantifies the energy deposited into a substance by radiation, while the Sievert accounts for the biological impact of that radiation, taking into consideration the type of radiation and its effect on human tissue. The Curie, although it is a historical unit that also measures radioactivity, is based on the activity of a sample of radium and is not part of the SI system, making the Becquerel the more appropriate and standard unit for current scientific use.