A sample of radioactive waste has a half-life of 30 years and an activity level of 2 curies. After how many years will the activity level of this sample be 0.25 curie?

Write a 4 paragraph essay about your role model, ! psychology

Gneiss is formed. the mineral grains in which granite are flattened under pressure

Arecent strip mall land development project included large amounts of paved surfaces. as a result of this project, groundwater levels in the developed area will most likely a. increase due to sealed artesian wells b. decrease as aquifers are not recharged c. decrease due to decreased surface runoff d. increase due to loss of unconfined aquifers e. increase due to a decrease in demand for fresh water