Question

please do 19,21

A) 1700 (B) 2000 19. INSECTICIDES The use of the insecticide DDT is no longer allowed in many countries because of its long-term adverse effects. If a farmer uses 25 pounds of active DDT, assuming its half-life is 12 years, how much will still be active after (A) 5 years? (B) 20 years? Compute answers to two significant digits. 12.4% per 0.03% per 20. RADIOACTIVE TRACERS The radioactive isotope technetium- 99m (39mTc) is used in imaging the brain. The isotope has a half- life of 6 hours. If 12 milligrams are used, how much will be present after (A) 3 hours? (B) 24 hours? Compute answers to three significant digits. 21. POPULATION GROWTH According to the CIA World Factbook, the population of the world was estimated to be about 6.8 billiorn people in 2008, and the population was growing continuously at a relative growth rate of 1.188%. If this growth rate continues, what would the population be in 2020 to two significant digits? lette wheel on red, and ess is then is lost though the his type of llars aid ure double ha teria 4 ia at bacter

Answer 1