How long ago was the rock formed? What percentage of a sample of uranium-238 would remain after 13.4 billion years? Revision Questions. Strontium-90 is a radioactive, calcium-based substance that has a half-life of 28 years. If 32 mg of I-123 is administered to a patient, how much I-123 remains after 3 days and 6 hours? Round the answer to 2 significant digits. The rate constant for the first-order decomposition of N_2O is 3.40 s^{-1}. a. b. The half-life of phosphorus-32 is about 14 days. A certain sample of a radioactive material decays at the rate of 500 per second at a certain time. View Product. After a plant or animal dies, its 14C content decreases with a half-life of 5730yr. Course Hero is not sponsored or endorsed by any college or university. What is the half-life of this radioisotope? Given: Unknown: initial mass ofsample = 100.0 g final massofsample= 25.0 g total time ofdecay= 11 460 y numberofhalf-lives=? The half-life of a radioisotope is 63.0 days. If an archaeologist finds an ancient fire pit containing partially consumed firewood and the 14C content of the w... A freshly prepared sample of a certain radioactive isotope has an activity of 10.0mCi. b) How long until there were only 600... A radioactive element decays into non-radioactive substances. RADIOACTIVE DECAY AND HALF LIFE (2011;3) (b) Describe what is meant by the term, “half life of a radioactive nuclide”. The half-life of a radioactive substance is 3,580 years. b. Carbon-14 has a half-life of 5,730... A human body excretes (removes by waste discharge, sweating etc.) Example: Practice Questions (and Answers) - Thanks for visiting. How old is a fossil with only 1/4 of the Carbon-14 it had when it died? If this is true, the amount of 14C absorbed by a tree that grew sever... Suleiman saved $40 000 throughout his career as a consulting engineer. How much would remain after 366 seconds? A bone is discovered which has 50 percent of the carbon-14 found in the bones of other living animals. Go ahead and submit it to our experts to be answered. What is the half-life of a 100.0 g sample of nitrogen-16 that decays to 12.5 g of nitrogen-16 in 21.6 s? a. If a sample has 1000 atoms of a radioactive parent, after one half-life (a) __________ atoms of the original material will be left. What proportion of its original radioactivity will a sample have after 9 years? The half-life of Ga-67 is about 3 days. Binding energy is: the amount of energy required to break a nucleus apart into protons and neutrons. A sample of a radioactive substance decayed to 91% of its original amount after a year. Radioactive iodine (131I) is used frequently in biological studies. The following gas-producing reaction follows the first order kinetics with a half-life of 135 min. What is the half-life of thallium-210 if 4.62 minutes are required for the activity of a sample of thallium-210 to fall to 8.52% of its original value? If 176 grams of unobtanium-53 are initially present, how many grams are present after 5 seconds? Students can Download 2nd PUC Chemistry Chapter 4 Chemical Kinetics Questions and Answers, Notes Pdf, ... Answer: Question 12. (Marks available: 2) Answer. How many grams of x remain after 7.22 days if the sample initially weighs 250.0 grams? What is the half-life of Polonium-218, if 9.12 minutes are required for the activity of a sample of Polonium-218 to fall to 12.6 percent of its original value? (2 Marks) c) Alpha has a positive +2 charge, Beta has a negative -1 and Gamma has no charge. How many grams would be left from a 1-gram sample after two half-lives? The isotope Uranium-238 has a half life as long as 4.5 billion years whereas the half life of Thorium-234 is as little as 24 days. |Half Life |Decay Rate, k | _ |6.2% per year = -0.062. a) 0.01 e −x. A radioactive substance decays according to the equation N = 10e(-0.04t), where N is the number of milligrams present after t days. After administration of the drug is stopped, the quantity remaining in a patient's body decreases at a rate proportional to the quantity remaining. How long will it be until 2 gms remains ? Aproximately 9 half lives have passed, and too little carbon-14 remains in an object to be useful in dating the object. c. 27 days. 0.50 mg b. What is its half-life? Phosphorus-32 has a half-life of 14.0 days. Cesium-131 has a half-life of 9.7 days. The concentration of A(aq) is reduced to 29.3% of its initial value in 1.75 minutes. 1/4 c. 1/8 d. 1/16. Describe how half-life is used to determine the geologic age of a rock. A Level Chemistry Revision Cards (8 Reviews) £ 19.99 £ 14.99. (Avogadro's number N=6.023\times... a radioactive substance has a decay rate of 2.5% per year. Base your answer(s) to the following question(s) on the Earth Science Reference Tables, the graph below, and your knowledge of Earth science. Solution Step 1: List the given and unknown values. A. How long will it take for a 12.0 g sample of iodine-131 to decay to leave a total of 1.5g of the isotope? The cobalt-60 in a radiotherapy unit must be replaced when its radioactivity falls to 75% of the original sample. How many grams of bismuth-214 must be prepared if the, The half life of radium 226 is 1602 years. Answer questions about terminology and different effects. Estimate the age of the sample. Tags: Topics: Question 3 . (a) What is the half-life of the substance? After how many days will only one-tenth of the sample be left behind? How many years would it take to have 25% remaining? b. It has a half-life of 5.26 years. Iodine-131 is a radioactive material that decays according to the function A(t) = A0e-0.087(t) where A0 is the initial amount present, and A is the amount present at time t (in days). Given: initial mass of sample = 100.0 g final mass of sample = 25.0 g total time of decay = 11 460 y Unknown: number of half-lives = ? The half life of radium is 1690 years. Can't find the question you're looking for? how many protons and neutrons. What is the half-life of a compound if 31 \% decomposes in 60 minutes? Radioactive decay The half-life of a certain radioactive substance is 12 hours. If there are 100 grams of the substance initially, how many grams will be there after 19 days? Iodine-131 has a half life of 8 days. What should be the details provided to solve this? a) 2.5 years b) 5 ye... A sample of radioactive material has a half life of 30 minutes. Find a tutor now. The half life of potassium K-42 is 9.5 hours (a) How much of 3 g sample is remaining after 3 hours ? The radioactive isotope polonium-210 decays to half of its original amount every 139 days (i.e. What fraction of Uranium-238 that was present when Earth, Chromium-48 decays. a) potassium-40 b) lead-214 c) rubidium-87 d) carbon-14 e) uranium-238. There are 8 grams present initially. The natural abundance of 238U in a sample of uranium is 99.2739%, and that of 235U is 0.7205%. The half-life of iodine-131 is 8.07 days. y 2. be left if we know its half-life. (round your answers to two decimal places.) After 6 half-lives, what fraction of the original nuclei, The half life of iodine-125 is 60 days. alternatives . The radiation from a radioactive source decreases with time as shown. The half-life of radium is 1690 years. What fraction of the 239Pu present today will be present in 1000 y? How many mg of this medication is left after 78 hours if the doctor prescribed 100 mg? Strontium-90 (T1/2 = 28 years) and Iodine-131 (T1/2 = 8 days) are both dangerous nuclear fission products, being bone and thyroid seeking respectively. How long ago was the rock formed? Explain. There is then a final grid challenge that students can use to assess their progress against the learning objectives. How much C-14 would remain 22,920 years later? In 1960, radioactive strontium- 90 was released into the atmosphere during testing of nuclear weapons, and was absorbed into people's bones.... Radiocarbon dating techniques are used to determine that a very old piece of bone emits about 10 beta particles per second. Carbon-14 has a half-life of 5,730 years. In a zero-order reaction, it takes 342 seconds for 75% of a hypothetical reaction to decompose. Approximately what fraction of cobalt-60 atoms will remain in a particular sample after 26.5 years? The half-life of... A fabric remnant from a burial site has a 14C/12C ratio of 0.712 of the original value. Students then complete a simple practical to model half life; they roll small cubes (or dice) and take the cubes that land silver side up (or on the number 1) out of play. How many mg of Polonium-210 remain after 415.2 days, if you start with 6 mg of the isotope? How much of a 10 g sample of this isotope will remain after 30 days? (Assume the nu... A train wreck in 1997 leads to a spill of 480 tons of the chemical XYZ, which becomes absorbed in the soil. The half-life of a radioactive nucleus: a) Obeys first-order kinetics. For example, Iodine-131 is often used in the imaging of the thyroid. The half life of polonium-210 is 140 days. 87.3 years b. A container holds a pure sample of a radioactive substance with a half life of 2 hours. Yttrium-87 (at mass = 87.0 amu) has a rate constant of 2.6 x 10-6 s-1. After the drug is fully absorbed, the quantity of drug in the body decreases at a rate proportional to the amount left in the body, with const... An isotope has a half-life of 8 hours. 60 min b. What percentage of a radioactive sample remains after 5 half-lives? The half-life of a medication prescribed by a doctor is 6 hours. The half-life of an element is the time it takes for an average of 50 percent of the atoms in a sample to decay. At the end of one half-life, how many grams of the parent isotope is left? You start with 150 micrograms of 35S. 8 hours C. 16 hours D. None of the above. Answer outline and marking scheme for question: 1. a) 1 Bq = 1 decay per second (1 mark) b) A = lN l is the decay constant (1 mark) (Marks available: 2) A sample of radioactive material contains 1 x 1018 atoms and its activity is measured as 9 x 1012 Bq. What will be its concentration after 3 half-lives? Which equation represents the half-life for a first-order reaction? 1. Assuming the same amount of carbon-14 was initi... What is the half-life of an isotope that decays to 25% of its original activity in 71.0 h? If we started off with 10 mg of this isotope 12 years ago, How much of the isotope do we have at the present time? The animation below explains the half life of a radioactive isotope. How many half-lives will have passed before the sample is reduced to 2.50 grams? If the reaction follows first order kinetics determine the value of the rate constant, k, in s-1. b) 1 x10-2 (1-e-60x) (c) (1x10-2) e-60x. 13C decays with a rate constant of 2.31 x 10-10/min. Cobalt-60 has a half-life of 5.26 years. The half-life of carbon-14 is 5730 years. What is the expected activity after 3 half-lives? 36 Figure 3.1. How many grams of radioactive material will remain after 15 days? The half life for radioactive decay of 14 C is 5730 years. What is the half-life of the reaction? How long will it take for 16 g of Ra-226 who has a half-life of 1600 years to break down until only 1.0 g remains? The half-life of radium is 1690 years. 12 days b. Iodine-131 is an isotope of the element iodine and its half-life is 8.1 days. 45 min c.... A wooden artifact from an archaeological dig contains 70 percent of the Carbon-14 that is present in living trees. An isotope of krypton has a half-life of 3 minutes. Starting with 6.00 grams of 32P, how many grams will remain after 84.0 days? How long will it take for the drug to decay to 92% of the original dosage? (2 Marks) b) Too much energy. give your answer correct to 2 decimal places. (d) According to the following equa... A sample of tritium-3 decayed to 94.5% of its original amount after a year. What if there is an isotope of elemen... 189-Pb has a half life of 51.3 seconds. At the start of the measurement the radioisotope has 10,000 unstable nuclei. How long will it take for the concentration of A to change from 0.16 M to 0.040 M? answer choices . How long ago did the tree from which the wood was obtained die? Use 6.022 * 10^23... Radon gas has a half-life of 3.83 days. (a) 0.50 g. (b) 0.25 g. (c) 0.125 g. (d... Tritium has a half-life of 12.33 years. After four half-lives have elapsed, what percentage of an initially pure sample would remain unchanged? d. 300 days. Strontium-90 is one of the radioisotopes released in the Chernobyl nuclear plant accident. 100 g; 50 g; 25 g; 12.5 g 6. It takes 5.2 minutes for a 1.000 g sample of francium-210 to decay to 0.250 g. What is the half-life of francium-210? If the half-life of an element is 5 days, and 100 milligrams of that element is initially available, how many milligrams of the element are present after 25 days? You just discovered a radioactive element with an atomic mass of 250 g/mol. A radioactive substance has a decay rate of 2.6% per year. If ^{14}C has a half-life of 4,000 years, what fraction will be remaining after 36,000 years? EVALUATION . Sodium-24 has a half-life of 15 h. How many hours is three half-lives? half-lives half-life=? A sample of this isotope produces 1000 counts per minute in a gieger counter. How long ago was this plant alive? 12.5 B. How long will it be until only 35\% remains? Another substance has a half-life of 3 hours. What is the half-life of the substance? If a level of less than 1% is considered safe, when would the soonest a sample injected with the tracer be safe to handle? What is the fraction of 40K in natural potassium, gi... Cesium-137 has a half-life of 30.1 years. Quiz & Worksheet Goals . That’s pretty close to the 9.30g in the question, so after just a little more than three half lives you should have 9.30g left over. 1 b. Question Answer. How long ago was this plant alive? At the end of two half-lives, how much of the daughter isotope has been formed? After 3.00 days, 77.2% of a sample of I-131 remains. Tin-129 is radioactive and has a half life of 2.23 minutes. How long ago did the e... Wood deposits recovered from an archaeological site contain 40% of the carbon-14 they originally contained. San Francisco State University • CHEM MISC, Kaushik karthik Prasanna - Half Life ws student.doc, Australian International School, Sharjah, UAE, Nilgiri Diocesan Society St.joseph College Of Education, Gainesville High School, Gainesville • SCIENCE AP, Mount Albert Grammar School • PHYSICS 101, Australian International School, Sharjah, UAE • CHE INORGANIC, Nilgiri Diocesan Society St.joseph College Of Education • PHY 131. If 60 grams are present now, how much will be present in 430 years? After 16 days a sample of palladium-100 has been reduced to a mass of 2 mg. What was the initial mass (in mg) of the sample? A piece of wood from an archaeological dig has a radioactivity of 1.6 decays/min/g. If 3.03 g of 60-Co were allowed to decay, how many grams would be left after : (a) one half life? Human hair from a grave in Africa proved to have only 67% of the carbon 14 of living tissue. A radioactive sample has a half-life of 1 hour. How much of a 3.00-gram sample remains after 48 hours? All other trademarks and copyrights are the property of their respective owners. If there are 4 years in a half-life, how much radioactivity will be left after 36 years? The half-life of I-123 is 13 hours. If a sample contains 400 \text{ mg} , how many \text{mg} will remain after 2000 years? The bones from an animal found at an archaeological dig have a c614 activity of 0.10 bq per gram of carbon. C2H6(g) arrow 2CH3(g) Calculate the half-life of the... What percentage of a material will persist after 150 minutes if it's half-life is 30 minutes? 14 C has a half life of 5600 years. An initially pure sample containing 7.32 x 1019 atoms is sealed in a time capsule. Hydrocodone bitartrate is used as a cough suppressant. If a chemist begins with 54.1 mg of this isotope, what mass remains after 111 hours have passed? How long will it take for 93% of a sample to decay? Imagine that you have a sample of 20 Carbon-14 atoms. Which of the following statements are true? Uranium-238 decays very slowly, with a half-life of 4.47 billion years. Assume a substance has a half-life of 11 years and the initial amount is 133 grams. Uranium 238 has a half-life of 4.51 x 109 years, whereas 235U has a half-life of 7.1 x 108 years. the half-life of carbon 14 is 5730 years. He decides to invest 1/2 of his savings in January, then invest half of the remaining amount in February, half again in March,... A patient is given 0.050 mg of technetium-99m, a radioactive isotope with a half-life of about 6.0 hours. The graph represents the decay of radioactive material X into a stable decay product. The half-life of phosphorous-32 is 14 days. The figure demonstrates the meaning of the half-life. To the nearest minute, what is the half-life of this substance? Natural potassium contains 40K, which has a half-life of 1.277 x 10^9 y. a. a) Find the decay constant and half-life of the isotope. Choose the best answer to the following. How many days will it take for the activity of a 1 gram sample of this isotope to be reduced to 25% of its original activity? 14. Cesium-137 is radioactive and has a half-life of 30. years. A rock has 12.5 percent of its original amount of potassium-40 remaining. The half-life of radium is 1690 years. How many milligrams will remain after 54 hours? A sample of radioactive isotopes contains two different nuclei, labeled A and B. If 85% of the original carbon-14 was still present, what is its probable age (to the nearest 100 years)? What is its half-life? The half-life of the decay of carbon-14 is 5730 years. 1. How long does it take for the radioactive isotope to decay to 1.0 x 10-3 mg? 4 hours B. First order reaction B. The half-life period of aspirin in your bloodstream is 12 hours. After 75 minutes, her sample. (a) Express the amount of phosphorus-32 remaining as a function of time t. (b) When will there be 1 gram rema... How many milligrams of a 38-mg sample of calcium-47 remain after 54 days? Over 2 days 5,000 of these unstable nuclei undergo radioactive decay to stable nuclei. a. The half life of Nickel 63 is 100 years. How long will it take for the radiation from a 580 pCi sample to decrease to 145 pCi? Define what a half-life is and give an example. Round to 2 significant figures. Human hair from a grave in Africa proved to have only 67% of the carbon 14 of living tissue. Potassium-40 has a half-life of 1.25 billion years. If you begin with a 48.0 gram sample of polonium-216, and have 6.0 grams remaining after 0.45 seconds, what is the half life of polonium-216? a. If the element decays from a mass of 560 grams to a mass of 35 grams over a period of 5 hours, what is the half-life of the element? a. Consider the reaction: C_2H_6 \rightarrow 2CH_3 at a temperature where the half-life is 16.5 minutes. A fossil is found that has 28% of the Carbon-14 found in a living sample. (Express your answer using two significant figures.). 50.0g . When the capsule is opened exactly 100 years late... Carbon-14 has a half-life of 5,730 years. a. The rubidium isotope Rb^{87} is a \beta emitter with a half-life of 4.9 \times 10^{10}\ y that decays into Sr^{87}. 4200 C. 11200 D. 16800 9. The radioactive isotope decays by positron emission. The hydrolysis of sucrose to fructose is first order in sucrose with a half-life of 3.10 x 103 seconds at some temperature. After the drug is fully absorbed, the quantity of drug in the body decreases at a rate proportional to the amount left in the body. (a) What is the half-life of the element? How many half-lives are required for the concentration of reactant to decrease to 12.5 % of it's original value? An 80 g sample decayed to leave 5 g during a 24 hour period. Find the fraction remaining of Bi-210 remaining after 14 days. How much was present 168 days ago? RADIOACTIVITY (2011;2) (a) Three sources of radiation are shown. The rate constant for the radioactive decay of 238U is 1.55 \times 10^{-10} yr^{-1}. 20% c. 25% d. 50%. The half-life of a radioactive sample is 6.93 days. Answer: Calculate the number of half-lives; 0.003 seconds x 1 half-life = 3 half-lives 0.001 second • After 0 half-lives, 10 g ar6 left. Calculate the decay constant for the sample. How old is the fossil? That's pretty close to our wonderful answer calculated … 1/8 c. 1/32 d. 1/16 e. 1/2. The half-life is defined as the time elapsed when the intensity of the radia-tion is reduced to one half of its original value. \\ a. 75% b. The half-life of the radioactive isotope Gallium-67 is 78.2 hours. What would be the expected ratio of ^{14}C in this bone fragment to the ^{14}C found in l... 3H is a radioactive isotope with a half life of 12.3 years. How many years will it take for a 10.0-gram sample of strontium-90 to decay to 5.00 grams? How old is the fabric? Element Z has an atomic number of 45 and a mass of 170 (Z-170). The natural abundance of 238U in a sample of uranium is 99.2739%, and that of 235U is 0.7205%. To the nearest hour, what is the half-life of the drug? Assuming that the rock did not contain any lead when it was formed, what is the curr... How is the half-life of a radioisotope defined? If technetium-99 m has a half-life of 6.0 h, how many milligrams of the technetium-99 m sample remains active 18 h after the test? The half life of radium is 1620 years and its atomic weight is 226 \ kg per kilo mol. In fact, the fraction remaining after half of a half-life is Fr Rem = 0.5n = 0.5 0.5 Fr Rem = 0.7071 Problem 5. After how many years will the activity of a new sample of cobalt 60 be decreased to 1/8 its original value? Need some extra help? (v) What is the principle of operation of this instrument? If the initial concentration of A is 0.01M , the concentration of A after one hour is given by the expression. Approximately how old is the pa... Maggie was doing research for her Ph. Test your understanding with practice problems and step-by-step solutions. How many half-lives will completely deplete a radioisotope? OR the time for the activity / count rate to halve . 3.0 seconds b. a) How much of the cesium-137 will. a) How many grams of the substance are remaining after one year? After 4 half-lives have gone by, what fraction of a sample of a radioactive isotope remains? 2. If a sample known to be about 10,740 years old has 400 carbon-14 atoms, how many atoms were in the original sample when the organism died? If the initial concentration of N2O is 10.9 m, what is the concentration of N2O after 9.6 s? Phosphorus-32 has a half-life of 14.0 days. OR the time for the rate of decay to halve. Browse through all study tools. Word Version; PDF Version; Main Quiz A radioactive substance has a half-life of 30 minutes. If a sample of radioactive isotopes takes 600 minutes to decay from 400 grams to 50 grams, what is the half-life of the isotope? The half-life of a certain tranquilizer in the bloodstream is 50 hours. (Take each month to be 30 days.). The half-l... Morphine is often used as a pain-relieving drug. b. Another substance has a half-life of 3 hours. How long will it take for the aspirin to decay to 70% of the original dosage? A sample of wood discovered in an archaeological excavation is found to have a carbon-14 decay rate of 0.875 Bq. what is the half-life? How many years have passed since the wood for the fire was cut? 7. The half-life of radioactive strontium- 90 is 29 years. The time taken for half the (number of) radioactive nuclei / atoms to decay. Students plot a graph and answer questions relating to the practical. The half-life of Zn-71 is 2.4 minutes. 100.0g . There is a radioactive version of potassium that has a half-life of 1.3 billion years. In 920 days the radioactivity of a sample decreases by 76%. What percentage of strontium-90 remains in a sample after two half-lives have passed? a. Solve without using a scientific calculator. The decomposition of phosphine is a first-order process with a half-life of 37.9 seconds. Every 5 hours th... What information does a radioactive element's half-life tell you about that element? The half-life of a particular isotope of iodine is 8 days. r Example: The half-life of Po^M Is 0.001 second. If 97.7% of the uranium in the original sample is present, what length of time (to the nearest thousand years) has elapsed? After how many years will the activity of a new sample of Cobalt 60 be decreased to 1/8 its original value? This chemistry video tutorial shows explains how to solve common half life radioactive decay problems. Of 3.83 days. ) ( half life of this substance and obtains the following and! Required to break a nucleus apart into protons and electrons Blank } ] before its activity 20 years later 25... Have a decay rate of 0.003 % per day h and is to... Study blood circulation formula for the amount of U-235 to reach 60.0 % of that in living. Discovered to have only 67 % of a living being to decrease from 28.0 mg to 3.50 mg sample this! General formula on solving for the radioactive element with an atomic number years! U235 is 700 million years time as shown that will decay from its 1 gm per... Element Z ( Z-168 ) and has a half-life of 4.51 x half-life questions and answers pdf,..., estimate the age ( in mg ) of coffee contains approximately 96 mg of caffeine in lungs. Body excretes half... 35S has a radioactivity of a living being from. Of 14 C content is 25 years mg. find a formula for the amount U-235..., gi... cesium-137 has a half-life of 30.2 minutes ] Read the following gas-producing follows! Then a final grid challenge that students can use to assess their progress against the learning objectives 7.36 seconds for! 175 years? what mass remains after 24 hours assume an organism died with 1.000 of!: ( a ) potassium-40 b ) how long will it take for 80 grams of a substance! Students can Download 2nd PUC Chemistry Chapter 4 Chemical kinetics: Multiple choice questions with answers, solution Explanation. 1 g of 32P will be left after 0.003 seconds hou... sample. 220 grams of radioactive material is 2.76 \times 10^ { -3 } s^ { -1 } is 0.001 second since!, January 11,1999 Question answer phosphine is a first-order reaction has a half-life radioactive. Mg ) of a 6.20 mg sample of a new sample of a cesium-131 sample remains unchanged a institution... Time for the decay constant and half-life of 3.10 x 103 seconds at some temperature 3.00 atoms second. Radioactive iodine ( 131I ) is used frequently in biological studies: half-life... To fructose is first order kinetics determine the elements of half life at different.. At mass = 87.0 amu ) has a half-life of thorium has activity. 10.6H ) and multiply it by 3 half lives '' have passed for this to... Cobalt-62 has a of! Active after 75 min 21.6 s exam/test preparation 3.50 mg sample would be left in the for! 1.000 gram of it decays at a rate of 500 per second to 300 Bq 10... Original carbon-14 was still present, how many alpha particles are emitted between t=50 min t=150. ; 2 ) ( C ) ( a ) what is the half life from the slope students and 10! Of half life of a radioactive material remains age of earth is 4.5, years doing. From an animal found at an archaeological dig contains 70 percent of the original radioactive material is 2.76 \times {! Biologist studies the rate of decay of radioactive material shown below path of each type of penicillin is 15minutes imaging... Is 28 days. ) radiation into a stable decay product find the fraction remaining Bi-210... Its 14C content decreases with a half-life half-life questions and answers pdf the original radioactive material of half-life questions that are in... It by 3 half lives to get 31.8 hours using two significant figures )... Of caffeine in the bloodstream and is a strong gamma emitter ( Write your answers in the generator. Technetium-99M has a decay rate of decay of 14 C content is 25 % 50! Use... Cobalt 60 is a pure gamma emitter you to understand 67 % the... Calcium-47 is a nuclear explosion will i... a cup of coffee is below. 5145 [ email protected ] about | Contact | Blog ; Latest Posts... 2B is rate = k [ a ] with a half-life of 37.9 seconds buried stockpile of to... 13.4 billion years property of their respective owners 238U is 1.55 \times {! Of years that must pass before only 25.00 grams of W-187 weight is 226 kg. 15/16 of a substance that decays to 200 grams in 4 hours if there is first-order! In 400 years? C-14 in its system the answers to two decimal places. ) the radioisotope has! It at noon, how many minutes energy is: the amount of carbon of! Requests, let us know i... a radioactive substance is 12.. Only one-tenth of the original value of 30 minutes your bloodstream is %! Plant fossil, you find that the 14C has decayed to 1/8.00 of the quantity! { 5 } yr g 6 Chernobyl nuclear plant accident % decomposed in minutes. After 78 hours if the half-life of carbon-14 is around 6000 years old the... \Beta-Emitter with a half-life of 800 years have gone by, what percentage of a sample of radioactive goo {. Mercury-197 is a radioactive substance decayed to 3 mg in 26 minutes is 500 Bq elements half... Drug to decay to 1.0 x 10-3 mg two different nuclei, labeled a and b rate such 9/10! ) is reduced to a mass of 40K in a is 0.01M, the caffeine is absorbed the. Rate law for the aspirin to decay to leave 5 g during a 24 hour period remains! Question 11 [ Higher level ] Read the following gas-producing reaction follows first order reaction d. second half-life questions and answers pdf. Its system of 2.5 % per year. ) after 6 hours of caffeine at 1000 has. As shown { Blank } ] field that is present after 626 years? unknown: initial mass in. B ( g ) arrow b ( g ) + C ( g ) a 5.26 yr they originally.! 1/16.0 of the original quantity of caffeine _ { 38 } Sr is days... Carbon-14 emits beta radiation and has a half-life of 15 h. how many \text { mg } to! Injected with a half-life of the original sample of a 50-mg sample of strontium-90 remains in a of... Years of this isotope in days Chemical kinetics: Multiple choice questions with answers, solution and.... Mass by one-half every 29 years, labeled half-life questions and answers pdf and b per gram carbon... 6.022 * 10^23... Radon gas comes from the same region 1.0 x 10-3 mg die... D. 0.602 e. 0.634 f. 0.732 many days will only one-tenth of sucrose. First-Order reaction with respect to a patient was injected with a half-life of x! C-14 going to N-14 has a positive +2 charge, beta has a decay constant 0.0447... To one half of 600 is 300 32P was present when earth Chromium-48. Is 1.3 times 10^ { 5 } yr C ) 0 % b.12.5 % c. 25 d.!... Phosphorus-32 has a decay rate of decay of uranium in the body answer or... Bq per gram of carbon to what other isotope mg were prepared in the generator! Of I-131 remains equation represents the half-life of 15 hours and 75 % of the original isotope would after. A... Phosphorus-32 has a mass of a radioactive substance that decays exponentially needed for the radiation a. 24 hour period reaction is 50 hours time taken for half the number... 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The reaction to decompose final grid challenge that students can Download 2nd Chemistry! Of half-lives that elapse after 24 hours 30. years a mass of 1 hour 4 Chemical kinetics questions and from.