20.0 hours after being ingested 74.5 % of the original radioactive atoms have decayed or been eliminated. If the biological half-life is. known to be 35.0 hours, what is the physical half-life of this isotope? State the time in hours to 1 decimal places but do NOT include units in your answer.

1. The decay of radioactive substance is given by 7 N = Noe (1), where N is the number of atoms present at time t, No is the initial number of atoms and T is the exponential decay constant, which is related to the decay rate of the element. The N 1 half-life thalf is the time required for the number to atoms to decay by half ( = No 2 Solve for thalf starting from equation (1) in terms of T. Note: Use MathType to enter in T. Do not use the letter "T" from the keyboard. Don't forget the multiplication sign between variables. Use the asterisk symbol (*) for multiplication or the multiplication symbol in the math editor (orange box). thalf = 0.693 X√ S No, that's not the correct answer.

Hello please someone help me answer this problem set, thank you! Part A: A particular smoke detector contains 1.05 μCi of  241Am241Am, with a half-life of 458 years.  The isotope is encased in a thin aluminum container. Calculate the mass of 241 Am in grams in the detector. Express your answer numerically in grams.   Part B:  Fears of radiation exposure from normal use of such detectors are largely unfounded. Identify reasons why 241 Am smoke detectors are perfectly safe. Select all that apply a. The penetrating power of αα radiation is limited. b. Ions get trapped by electrodes. c. The amount of americium is very little. d. The number of αα particles leaving the case is low. e. The detector has a plastic cover.  f. The detector is housed in an aluminum case.

The uranium isotope U-238 has a half-life of about 4.5 × 109 years. i) BOOKWORK Consider 1 mole (238 gm) of isotopically pure uranium U-238. Calculate its activity, and sketch a graph of the activity of the U-238 over the next ten billion years or so. Label the axes with appropriate numbers and units. Mark on the graph the half-life and the characteristic time of decay. ii) UNSEEN The uranium isotope U-238 decays through a chain of fourteen relatively short-lived radionuclides with half-lives of less than one million years before reaching a stable isotope of lead. Bricks, sand, tiles and other building materials typically have an activity of about 50 Bq per kg due to their primordial uranium content, the uranium made in stars and later present in the materials making up our rocks. Estimate the concentration of U-238 in building materials. First consider only the U-238, and then refine your estimate by taking the decay chain into account.

A purified sample of Mo-99 contains 370 million Bq. a. What mass does this represent if the half-life of Mo-99 is 66 hours? b. What will be the activity of its decay product, Tc-99m in 10 hours if the Tc-99m has a half-life of 6 hours?

The counting rate from a radioactive source is 4000 counts per second at time t=0. After 10 seconds, the counting rate is 1000 counts per second. a)What is the half-life?                                                                             b)What is the counting rate after 20 seconds?

Determine the half-life (in s) of a radioactive sample that has a decay rate of 3.30 ✕ 1011 Bq when it contains 1.70 ✕ 1015 nuclei.  s

A patient is injected 465 MBq of radioactive isotopes with a half life of 110 minutes. How much radioactivity is left in his body after 24 hours? Select one: a. 0.053 MBq b. 4.98 MBq c. 318.63 MBq d. 373.85 MBq

8. The half-life for a radioactive isotope is 4.00 × 10⁹ yr. Determine the age (in years) of a rock specimen that contains sixty percent of its original number of radioactive atoms. years 0 ssi sf60 ss” 50 ssf6€ ssf60 sta £60

A radioactive sample is prepared; 10.78 hours later, only 1/16th of the original sample remains. What is the half-life of this radioactive sample in hours? Round to one decimal place.