32. A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 102º molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes? 1.00 x 10* molecules...

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Extracted text: 32. A first-order reaction has a half-life of 20.0 minutes. Starting with 1.00 × 102º molecules of reactant at time t = 0, how many molecules remain unreacted after 100.0 minutes? 1.00 x 10* molecules 2.00 × 101º molecules 3.20 × 1016 molecules 5.00 x 1020 molecules A. В. С. D. Е. none of these choices is correct 33. Carbon-14 is a radioactive isotope which decays with a half-life of 5730 years. What is the first-order rate constant for its decay, in units of yearsl? 5.25 x 10$ years' В. 1.21 x 104 years А. С. 1.75 x 104 years D. 3.49 x 10“ years" 3.97 x 10' years E. 34. The radioactive isotope tritium decays with a first-order rate constant k of 0.056 year". What fraction of the tritium initially in a sample is still present 30 years later? A. 0.19 В. 0.60 C. 0.15 2.8 x 1038 none of these choices is correct D. Е.