A certain radioactive material decays exponentially. The percent, P, of the material left after years is given by P(t) = 100(1.2). a. Determine the half-life of the substance. b. How fast is the substance decaying at the point where the half-life is reached? The substance is decaying at a rate of about -3.8% per year at the time 9.12 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 6.8 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 3.8 years where the half-life is reached None of the above

A certain radioactive material decays exponentially. The percent, P, of the material left after years is given by P(t) = 100(1.2). a. Determine the half-life of the substance. b. How fast is the substance decaying at the point where the half-life is reached? The substance is decaying at a rate of about -3.8% per year at the time 9.12 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 6.8 years where the half-life is reached The substance is decaying at a rate of about -9.12% per year at the time 3.8 years where the half-life is reached None of the above

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter34: Frontiers Of Physics

Section: Chapter Questions

Problem 3PE: (a) Estimate the mass of the luminous matter in the known universe, given there are 1011 galaxies,...

See similar textbooks

Similar questions

(a) Estimate the mass of the luminous matter in the known universe, given there are 1011 galaxies, each containing 1011 stars of average mass 1.5 times that of our Sun. (b) How many protons (the most abundant nuclide) are there in this mates? (c) Estimate the total number of particles in the observable universe by multiplying the answer to (b) by two, since there is an electron for each proton, and then by 109, since there are far more particles (such as photons and neutrinos) in space than in luminous matter.
(a) Write the decay equation for the decay of 235U. (b) What energy is released in this decay? The mass of the daughter nuclide is 231.036298 u. (c) Assuming the residual nucleus is formed in its ground state, how much energy goes to the particle?
What fraction of a radioactive sample has decayed after two half-lives have elapsed?
(a) If the average molecular mass of compounds in food is 50.0 g, how many molecules are mere in 1.00 kg at food? (b) How many ion pairs are created in 1.00 kg of food, if it is exposed to 1000 Sv and it takes 32.0 eV to create an ion pair? (c) Find the ratio of ion pairs to molecules. (d) If these ion pairs recombine into a distribution of 2000 new compounds, how many parts per billion is each?
(a) Calculate the energy released in the a decay of 238U . (b) What fraction of the mass of a single 238U is destroyed in the decay? The mass of 234Th is 234.043593 u. (c) Although the fractional mass loss is large for a single nucleus, it is difficult to observe for an entire macroscopic sample of uranium. Why is this?
RADIOACTIVITY. LAW OF RADIOACTIVE DECAY Activity units: 1 Ci = 3.7 × 1010 Bq 1. Nuclear decay law: N = Noe¬at, The law of radioactive decay gives the quantitative relationship between the original number of nuclei present at time zero No and the number N at a later time t (sec), where e = 2.71828... is the base of the natural logarithm, and 2 is the decay constant for the nuclide (1/s). 2. Relationship between decay constant 1 and isotop half-life T1/2: 0.693 T1/2 1= In(2) Half-life Modality Radioisotope T1/2 where a is decay constant (1/s), T1/2 is isotope half- life (s). Carbon-11 20 minutes PET Fluorine-18 110 minutes PET Copper-64 | 12.7 hours PET 3. Activity or decay rate of a radioactive source A: Gallium-67 AN A = At where A is activity or decay rate of a radioactive lodine-123 source (Bq), N is number of nuclei present at time t Thallium-201 (s ), 2 is decay constant (1/s). 78.3 hours SPECT | 68 minutes Gallium-68 Technetum-99m PET 6.02 hours SPECT Indium-111 | 67.3 hours SPECT…
1. The half-life of a radioactive substance is the time it takes for half of the substance to decay. The radioactive iodine isotope I-131, which has a half-life of 8 days, is used to treat hyperthyroidism. Solve 400 - 3.125 to find how many days t it will take for 400 millicuries of I-131 to decay to 3.125 millicuries. A 56 days в 7days C 8 days D 128 days 2. In the year 2000, the population of Mexico was about 100 million, and was growing by approximately 1.53% per year. At this growth rate, the function Ax) = 100(1.0153)* gives the population, in millions, x years after 2000. Using this model and a graph of the function, in what year would the population reach 109 million? Round your answer to the nearest year. 2006 C 2005 D 2007 A в 2008 3. Use a graph to solve 3* - 100. A x-4.2 в х-2.1 C x- 0.2 D x-0.1
NUCLEAR CHEMISTRY: Consider the nuclei Sn with an atomic number of 50 and mass number is 117 . Determine its mass defect in kilograms if its atomic mass is 116.956 amu. The mass of a proton and neutron are 1.0073 and 1.0087 amu, respectively. Express your answers in three decimal places in scientific notation, i.e., 6.022e23 to represent 6.022x 105
RADIOACTIVITY. LAW OF RADIOACTIVE DECAY Activity units: 1 Ci = 3.7 × 101º Bq 1. Nuclear decay law: N = Noe¬at, The law of radioactive decay gives the quantitative relationship between the original number of nuclei present at time zero No and the number N at a later time t (sec), where e = 2.71828... is the base of the natural logarithm, and 2 is the decay constant for the nuclide (1/s). 2. Relationship between decay constant 2 and isotop half-life T1/2: In(2) 0.693 Radioisotope Half-life Modality T1/2 T1/2 Carbon-11 20 minutes PET where a is decay constant (1/s), T1/2 is isotope half- life (s). 3. Activity or decay rate of a radioactive source A: ΔΝ Fluorine-18 110 minutes PET Copper-64 12.7 hours PET Gallium-67 78.3 hours SPECT Gallium-68 68 minutes PET = AN Technetum-99m 6.02 hours SPECT Δt where A is activity or decay rate of a radioactive source (Bq), N is number of nuclei present at time t (s ), 1 is decay constant (1/s). 4. Activity A of a radioactive source at a time t:…
A- The half-life of the radioactive nucleus Ra(88, 226) is about 1.6 ×10^3 yr. what is the decay rate after the sample is 2.6×10^3 yr old and how many nuclei left, where No=3.0 ×10^19 nuclei.
B. Carbon-14 is a radioactive isotope of carbon that has a half-life of 5600 years. It is used extensively in dating organic material that is tens of thousands of years old. Model the differential equation of the decay of the isotope if m is the mass and t is the time Calculate the constant using the half-life time. What fraction of the original amount of Carbon-14 in a sample would be present after 10,000 years? i) ii)
The number of radioactive atoms in a sample decay as the emission of radiation proceeds and this may be described by an exponential decay N(t) = N0exp(-t/τ) where τ is the decay time. What is the decay time τ if the half-life t1/2 = 3hrs? Select one: a. 8.15 hours b. 90 mins. c. 260 mins. d. 3 hours.