A radioisotope is found to decrease from 3.600 x 1024 radioactive atoms to 1.125 x 1023 radioactive atoms in 80,000 years.
What is the radioisotope's Half-Life?
time would it take for 252 ram samnle of Technetium-99 (half life = 2.13 x 105

Skills of homo sapiens were found an excavation. the skulls were preserved because the bodies were frozen. so, these fossils are (blank) fossils.the image shows the evolution of skulls beginning 2 to 3 million years ago. based on the image, modern human skulls(blank) ape skulls.

Which is the most concentratic acid

According to the passage, which of these is true about gray water systems? a) gray water systems use plants that require less water. eliminate b) gray water systems require the use of less fossil fuels. c) gray water systems reduce the amount of fresh water used. d) gray water systems reduce the amount water used by shower heads.