Question

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NAME 24. (6 points) The radioactive series for the decay of thorium-228 is given below, along with the half-life for the isotope that decays in the process REACTION HALF-LIFE A 2 Th? 2 Ra + He 1.9 years B 3Ra -Rn He 3.6 days c | 2 [Rn- 21: Po + t He | 55 seconds D Po2PbHe 0.15 seconds A. Indicate which would be the rate-determining step in the process above by writing the letter (A,B....) of the step in this space: B. Based on your answer to part A, estimate the amount of time required for the decay of 3.0g of thorium-228 to produce 1.0g of lead-208. Hint Your estimation may require both F 2. B? G ? 201.TI > 2 s TI + He 2ur Pb +.ae Lead-208 is stable 61 minutes 2ioue | 3 minutes approximations about kinetics and approximate values for the masses of isotopes.

Answer 1

24 step l s 0. 6 3 0-693 0- 364 Pb-208 20s 2 28 208

2.302 %; achvity afferv - a 303 22 8 228 /208 2.303 1g (3310. 3 X 20 396 0 . 36471 ears ), 244 건ear