Multiple ChoiceHow long will it take for 80% of a 1.20-mg sample of Rn-220 to decay? The half-life of Rn-220 is 55.6 s.116views
Multiple ChoiceA sample of Th-219 requires 3.84 × 10−6 seconds to decay to 1.50 mg. What was the initial mass of the sample of Th-219? (t 1/2 for Th-219 = 1.05 × 10−6 s)103views
Multiple ChoiceHow many mg of a 3.50-mg sample of Tc-99 will remain after 4 half-lives have passed?108views
Multiple ChoiceFor the radioactive decay of lead-202 the decay constant is 1.32 x 10-5 yr-1. How long will it take in hours to decrease to 53% of its initial amount?69viewsHas a video solution.
Multiple ChoiceDuring World War I radium-226 was used in the manufacturing of luminous paint. If it takes 2.12 x 104 days for its degradation to be 2.49% complete, what is its decay constant?70viewsHas a video solution.
Multiple ChoiceIf the decay constant for polonium-209 is 6.80 x 10-3 ys-1, what fraction of it remains after 1.1 x 104 years?72viewsHas a video solution.
Textbook QuestionFluorine-18 undergoes positron emission with a half-life of 1.10 x 10^2 minutes. If a patient is given a 250 mg dose for a PET scan, how long will it take for the amount of fluorine-18 to drop to 75 mg? (a) 56 minutes (b) 96 minutes (c) 132 minutes (d) 191 minutes522viewsHas a video solution.
Textbook QuestionIn a cave in Oregon, archaeologists found bones, plant remains, and fossilized feces. DNA remaining in the feces indi-cates their human origin but not their age. To date the remains, the decay rate was measured and found to be 2.71 disinte-grations/min per gram of carbon. Currently living organisms have a decay rate of 15.3 disintegrations/min per gram of carbon, and the half-life of 14C is 5715 years. How old are the remains? (a) 1460 years (b) 9900 years (c) 14300 years (d) 18600 years172viewsHas a video solution.
Textbook QuestionThe accompanying graph illustrates the decay of 8842Mo, which decays via positron emission. (b) What is the rate constant for the decay? [Section 21.4]197viewsHas a video solution.
Textbook QuestionThe accompanying graph illustrates the decay of 8842Mo, which decays via positron emission. (a) What is the halflife of the decay? [Section 21.4] 362viewsHas a video solution.
Textbook QuestionThe accompanying graph illustrates the decay of 8842Mo, which decays via positron emission. (c) What fraction of the original sample of 8842Mo remains after 12 min? [Section 21.4] 269viewsHas a video solution.
Textbook QuestionCalculate the binding energy a uranium-235 nucleus in units of MeV/nucleon. The mass of an 235U atom is 235.043 929, the mass of a proton is 1.007 28, the mass of a neutron is 1.008 67, and the mass of an electron is 5.486 x 10^-4. (1 MeV = 1.60 x 10^-13 J) (a) 2.84 MeV/nucleon (b) 1.70 x 10^3 MeV/nucleon (c) 11.3 MeV/nucleon (d) 7.62 MeV/nucleon1762viewsHas a video solution.
Textbook QuestionHow much energy in kJ/mol is released by the fission of uranium-235 to form barium-140 and krypton-93? The atomic masses are (a) 6.59 x 10^9 kJ/mol (b) 1.66 x 10^10 kJ/mol (c) 1.98 x 10^11 kJ/mol (d) 1.66 x 10^16 kJ/mol353viewsHas a video solution.
Textbook QuestionEach statement that follows refers to a comparison between two radioisotopes, A and X. Indicate whether each of the following statements is true or false. (a) If the half-life for A is shorter than the half-life for X, A has a larger decay rate constant.206viewsHas a video solution.
Textbook QuestionSome watch dials are coated with a phosphor, like ZnS, and a polymer in which some of the 1H atoms have been replaced by 3H atoms, tritium. The phosphor emits light when struck by the beta particle from the tritium decay, causing the dials to glow in the dark. The half-life of tritium is 12.3 yr. If the light given off is assumed to be directly proportional to the amount of tritium, by how much will a dial be dimmed in a watch that is 50 yr old?679viewsHas a video solution.
Textbook QuestionIt takes 4 h 39 min for a 2.00-mg sample of radium-230 to decay to 0.25 mg. What is the half-life of radium-230?370viewsHas a video solution.
Textbook QuestionCobalt-60 is a strong gamma emitter that has a half-life of 5.26 yr. The cobalt-60 in a radiotherapy unit must be replaced when its radioactivity falls to 75% of the original sample. If an original sample was purchased in June 2016, when will it be necessary to replace the cobalt-60?1932viewsHas a video solution.
Textbook QuestionThe cloth shroud from around a mummy is found to have a 14C activity of 9.7 disintegrations per minute per gram of carbon as compared with living organisms that undergo 16.3 disintegrations per minute per gram of carbon. From the half-life for 14C decay, 5715 yr, calculate the age of the shroud.757viewsHas a video solution.
Textbook QuestionPotassium-40 decays to argon-40 with a half-life of 1.27 * 109 yr. What is the age of a rock in which the mass ratio of 40Ar to 40K is 4.2?1372viewsHas a video solution.
Textbook QuestionOne of the nuclides in spent nuclear fuel is U-235, an alpha emitter with a half-life of 703 million years. How long will it take for the amount of U-235 to reach 10.0% of its initial amount?2037viewsHas a video solution.
Textbook QuestionHow much energy must be supplied to break a single aluminum-27 nucleus into separated protons and neutrons if an aluminum-27 atom has a mass of 26.9815386 amu? How much energy is required for 100.0 g of aluminum-27? (The mass of an electron is given on the inside back cover.)495viewsHas a video solution.
Textbook QuestionA radioactive sample contains 1.55 g of an isotope with a halflife of 3.8 days. What mass of the isotope remains after 5.5 days?1605views1rankHas a video solution.
Textbook QuestionA sample of F-18 has an initial decay rate of 1.5 * 105>s. How long will it take for the decay rate to fall to 2.5 * 103>s? (F-18 has a half-life of 1.83 hours.)1423views1rankHas a video solution.
Textbook QuestionThe half-life of indium-111, a radioisotope used in studying the distribution of white blood cells, is t1/2 = 2.805 days. What is the decay constant of 111In?560viewsHas a video solution.
Textbook QuestionThe atomic masses of nitrogen-14, titanium-48, and xenon-129 are 13.999234 amu, 47.935878 amu, and 128.904779 amu, respectively. For each isotope, calculate (a) the nuclear mass.430viewsHas a video solution.
Textbook QuestionThe decay constant of plutonium-239, a waste product from nuclear reactors, is 2.88 * 10-5 year - 1. What is the half-life of 239Pu?766viewsHas a video solution.
Textbook QuestionBased on the following atomic mass values:1H, 1.00782 amu; 2H, 2.01410 amu; 3H, 3.01605 amu; 3He, 3.01603 amu; 4He, 4.00260 amu—and the mass of the neutron given in the text, calculate the energy released per mole in each of the following nuclear reactions, all of which are possibilities for a controlled fusion process: (b) 21H + 21H¡32He + 10n528viewsHas a video solution.
Textbook QuestionPolonium-209, an a emitter, has a half-life of 102 years. How many alpha particles are emitted in 1.0 s from a 1.0 ng sample of 209Po?677viewsHas a video solution.
Textbook QuestionA mammoth skeleton has a carbon-14 decay rate of 0.48 disintegration per minute per gram of carbon (0.48 dis>min # g C). When did the mammoth live? (Assume that living organisms have a carbon-14 decay rate of 15.3 dis>min # g C and that carbon- 14 has a half-life of 5715 yr.)1151viewsHas a video solution.
Textbook QuestionIodine-131 is a convenient radioisotope to monitor thyroid activity in humans. It is a beta emitter with a half-life of 8.02 days. The thyroid is the only gland in the body that uses iodine. A person undergoing a test of thyroid activity drinks a solution of NaI, in which only a small fraction of the iodide is radioactive. (c) A normal thyroid will take up about 12% of the ingested iodide in a few hours. How long will it take for the radioactive iodide taken up and held by the thyroid to decay to 0.01% of the original amount?663viewsHas a video solution.
Textbook QuestionA sample of 37Ar undergoes 8540 disintegrations/min initially but undergoes 6990 disintegrations/min after 10.0 days. What is the half-life of 37Ar in days?178viewsHas a video solution.
Textbook QuestionRadioactive decay exhibits a first-order rate law, rate = -∆N/∆t = kN, where N denotes the number of radio-active nuclei present at time t. The half-life of strontium-90, a dangerous nuclear fission product, is 29 years. (a) What fraction of the strontium-90 remains after three half-lives?281viewsHas a video solution.
Textbook QuestionPotassium ion, K+, is present in most foods and is an essen-tial nutrient in the human body. Potassium-40, however, which has a natural abundance of 0.0117%, is radioactive with t1/2 = 1.25 x 10^9 years. What is the decay constant of 40K? How many 40K+ ions are present in 1.00 g of KCl? How many disintegration/s does 1.00 g of KCl undergo?459viewsHas a video solution.
Textbook QuestionThe electronic systems on the New Horizons spacecraft, which launched on January 19, 2006, and reached its closest approach to Pluto on July 14, 2015, were powered by elec-tricity generated by heat. The heat came from the radioac-tive decay of 238Pu in the 11 kg of 238PuO2 fuel onboard. The generator provided 240 W when the spacecraft was launched. If the power output is directly proportional to the amount of 238Pu in the generator, what was the power output when the spacecraft reached Pluto? The half-life of 238Pu is 87.7 y.152viewsHas a video solution.
Textbook QuestionIf 1.0 g of matter is converted to energy, how much energy is formed?440views1commentsHas a video solution.
Textbook QuestionA typical home uses approximately 1.0 * 103 kWh of energy per month. If the energy came from a nuclear reaction, what mass would have to be converted to energy per year to meet the energy needs of the home?428views1rankHas a video solution.
Textbook QuestionCalculate the mass defect and nuclear binding energy per nucleon of each nuclide. a. Li-7 (atomic mass = 7.016003 amu)1153views1commentsHas a video solution.
Textbook QuestionA laboratory rat is exposed to an alpha-radiation source whose activity is 14.3 mCi. (a) What is the activity of the radiation in disintegrations per second? In becquerels?358viewsHas a video solution.
Textbook QuestionCalculate the quantity of energy produced per gram of U-235 (atomic mass = 235.043922 amu) for the neutron-induced fission of U-235 to form Xe-144 (atomic mass = 143.9385 amu) and Sr-90 (atomic mass = 89.907738 amu) (discussed in Problem 57).1457views1rankHas a video solution.
Textbook QuestionUranium-238 has a half-life of 4.47 * 109 years and decays through a series of events to yield lead-206. Estimate the age of a rock that contains 105 mmol of 238U and 33 mmol of 206Pb. Assume all the 206Pb is from the decay of 238U.733viewsHas a video solution.
Textbook QuestionThe age of an igneous rock that has solidified from magma can be found by analyzing the amount of 40K and 40Ar. Potassium-40 emits a positron to produce argon-40 and the half-life of 40K is 1.25 * 109 years. What is the age of a rock whose 40Ar/40K ratio is 1.42?419viewsHas a video solution.
Textbook QuestionA 75-kg human has a dose of 32.8 rad of radiation. How much energy is absorbed by the person's body? Compare this energy to the amount of energy absorbed by the person's body if he or she jumped from a chair to the floor (assume that the chair is 0.50 m from the ground and that all of the energy from the fall is absorbed by the person).553viewsHas a video solution.
Textbook QuestionWhy does a given nucleus have less mass than the sum of its constituent protons and neutrons?190viewsHas a video solution.
Textbook QuestionIn an endothermic chemical reaction, do the products have more mass, less mass, or the same mass as the reactants? Explain.335viewsHas a video solution.
Textbook QuestionSuppose a patient is given 1.55 mg of I-131, a beta emitter with a half-life of 8.0 days. Assuming that none of the I-131 is eliminated from the person's body in the first 4.0 hours of treatment, what is the exposure (in Ci) during those first four hours?781viewsHas a video solution.
Textbook QuestionComplete each nuclear equation and calculate the energy change (in J>mol of reactant) associated with each (Be-9 = 9.012182 amu, Bi-209 = 208.980384 amu, He-4 = 4.002603 amu, Li-6 = 6.015122 amu, Ni-64 = 63.927969 amu, Rg-272 = 272.1535 amu, Ta-179 = 178.94593 amu, and W-179 = 178.94707 amu). a. _____ +94Be ¡63Li + 42He1047viewsHas a video solution.
Textbook QuestionCalculate the binding energy (in MeV/nucleon) for the following nuclei. (b) 84Kr (atomic mass = 83.91151)463viewsHas a video solution.
Textbook QuestionCalculate the binding energy (in MeV/nucleon) for the following nuclei. (a)58Ni (atomic mass = 57.93535)486viewsHas a video solution.
Textbook QuestionThe nuclear masses of 7Be, 9Be, and 10Be are 7.0147, 9.0100, and 10.0113 amu, respectively. Which of these nuclei has the largest binding energy per nucleon?415viewsHas a video solution.
Textbook QuestionWhat is the energy change ∆E (in kJ/mol) when an a particle is emitted from 174Ir? The atomic mass of 174Ir is 173.96666 the atomic mass of 170Re is 169.95804, and the atomic mass of a 4He atom is 4.00260.334viewsHas a video solution.
Textbook QuestionA typical nuclear reactor produces about 1.0 MW of power per day. What is the minimum rate of mass loss required to produce this much energy?298viewsHas a video solution.
Textbook QuestionFind the binding energy in an atom of 3He, which has a mass of 3.016030 amu.634viewsHas a video solution.
Textbook QuestionThe radioactive isotope 100Tc decays to form the stable iso-tope 100Mo. (b) Only one of the pathways is observed. Calculate the energy released by both pathways, and explain why only one is observed. Relevant masses are: 100Tc = 99.907 657, 100Mo = 99.907 48, electron = 0.000 548 6.204viewsHas a video solution.
Textbook QuestionThe half-life of 238U is 4.5 * 109 yr. A sample of rock of mass 1.6 g produces 29 dis>s. Assuming all the radioactivity is due to 238U, find the percent by mass of 238U in the rock.921viewsHas a video solution.
Textbook QuestionThe half-life of 232Th is 1.4 * 1010 yr. Find the number of disintegrations per hour emitted by 1.0 mol of 232Th.569views1commentsHas a video solution.
Textbook QuestionHow much energy (in kJ/mol) is produced in the following fission reaction of plutonium-239? 710viewsHas a video solution.
Textbook QuestionHow much energy (in kJ/mol) is released in the fusion reaction with 2H and 3He? 589viewsHas a video solution.
Textbook QuestionHow much energy (in kJ/mol) is released in the fusion reaction of 1H and 2H atoms? 619viewsHas a video solution.
Textbook QuestionThe nuclide 18F decays by both electron capture and b+ decay. Find the difference in the energy released by these two processes. The atomic masses are 18F = 18.000950 and 18O = 17.9991598.306viewsHas a video solution.
Textbook QuestionA 255-gram laboratory rat is exposed to 23.2 rads. How many grays did the rat receive? How many joules were absorbed by the rat?180viewsHas a video solution.
Textbook QuestionThe maximum level of radon in drinking water is 4.0 pCi (4.0 x 10^-12Ci) per milliliter. (a) How many disintegrations occur per minute in 1 mL of water at the maximum radon level? (b) If the radioactive isotope is 222Rn(t1/2 = 3.8 days), how many 222Rn atoms are present in 1 mL of the water?147viewsHas a video solution.
Textbook QuestionNitrogen-16 is formed in the cooling water flowing through a hot reactor core in a nuclear power plant. It is formed when oxygen captures a neutron and then emits a b par-ticle. Determine the activity of 50.0 mg of 16N in units of Bq and Ci.855viewsHas a video solution.
Textbook QuestionA proposed nuclear theory suggests that the relative abun-dances of the uranium isotopes 235U and 238U were approximately equal at the time they were formed. Today, the observed ratio of these isotopes is 7.25 x 10^-3. Give that the half-lives for radioactive decay are 7.04 x 19^8 are y for and 4.47 x 10^9 y for , calculate the age of the elements.166viewsHas a video solution.
Textbook QuestionA small sample of wood from an archaeological site in Clo-vis, New Mexico, was burned in O2 and the CO2 produced was bubbled through a solution of Ba(OH)2 to produce a precipitation of BaCO3. When the BaCO3 was collected by filtration, a 1.000 g sample was found to have a radioactivity of 4.0 x 10^-5 Bq. The half-life of 14C is 5715 y, and living organisms have a radioactivity due to 14C if 15.3 disintegrations/min per gram of carbon. If the analysis was carried out in 1960, what is the date of the Clovis site?167viewsHas a video solution.
Textbook QuestionPolonium-210, a naturally occurring radioisotope, is an alpha emitter, with t1/2=138 d. Assume that a sample fo 210Po with a mass of 0.700 mg was placed ina 250.0-mL flask, which was evacuated, sealed, and allowed to sit undisturbed. What would the pressure be inside the flask (in mmHg) at 20 degrees Celsius after 365 days if all the alpha particles emitted has become helium atoms?471viewsHas a video solution.
Textbook QuestionImagine that you have a 0.007 50 M aqueous MgCl2 solu-tion, prepared so that it contains a small amount of radio-active 28Mg. The half-life of 28Mg is 20.91 h, and the initial activity of the MgCl2 solution is 0.112 mCi>mL. Assume that 20.00 mL of this MgCl2 solution is added to 15.00 mL of 0.012 50 M aqueous Na2CO3 solution and that the resultant precipitate is then removed by filtration to yield a clear filtrate. After a long break to go for a run, you find that the activity of the filtrate measured 2.40 h after begin-ning the experiment is 0.029 mCi>mL. What are the molar concentrations of Mg2+ and CO32- in the filtrate, and what is the solubility product constant of MgCO3?179viewsHas a video solution.
Open QuestionA moon rock collected by the Apollo mission is estimated to be 3.80 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass of 206 Pb in the rock, given that it currently contains 1.180 g of 238 u? The half-life of 238U is 4.47×109 years.62viewsHas a video solution.
Open QuestionThe most stable nucleus in terms of binding energy per nucleon is 56Fe. If the atomic mass of 56Fe is 55.9349 amu, calculate the binding energy per nucleon for 56Fe, in joules. The mass of a hydrogen atom is 1.0078 amu, and the mass of a neutron is 1.0087 amu. (1 J = 1 kg・m²/s², 1 amu = 1.66 × 10-27 kg)106viewsHas a video solution.
Open QuestionWhat fraction of a reactant has been consumed after 4 half-lives in a first-order reaction?33viewsHas a video solution.
Open QuestionA fossil is found to have a 14C level of 76.0% compared to living organisms. How old is the fossil?48viewsHas a video solution.
Open QuestionWhat is the rate constant of a first-order reaction when 20.0% of a reactant remains after 30.0 s?28viewsHas a video solution.
Open QuestionA fossil is found to have a 14c level of 64.0% compared to living organisms. How old is the fossil?24viewsHas a video solution.
Open QuestionA fossil is found to have a 14C level of 85.0% compared to living organisms. How old is the fossil?27viewsHas a video solution.