Version 001 Nuclear tubman (IBII201516) 1

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1 Version 001 Nuclear tubman (IBII201516) 1 This print-out should have 21 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. AP B 1993 MC points Atoms of isotopes of the same element contain the same number of 1. protons but a different number of neutrons. correct 2. protons as neutrons. 3. neutrons but a different number of protons.. electrons but a different number of protons. 5. neutrons as electrons. Atomsofisotopesofthe sameelement have the same number of protons and an equal number of electrons. The numbers of neutrons for isotopes are different. Serway CP (part 1 of 2) 10.0 points Find the speed an alpha particle requires to come within m of a gold nucleus. Coulomb s constant is N m 2 /C 2, the charge on an electron is C, and the mass of the alpha particle is kg. Correct answer: m/s. Let : r min = m, k e = N m 2 /C 2, q = C, and m a = kg. At the point of closest approach the kinetic energy is zero, so v = = PE f = KE i k e (2e)(9e) r min = 1 2 m av 2 2k e (2e)(9e) = m a r min 316k e e 2 m a r min 316( N m 2 /C 2 ) ( kg)( m) ( C) = m/s. 003 (part 2 of 2) 10.0 points Find the energy of the alpha particle. Correct answer: MeV. KE i = 1 2 m av 2 = 1 2 ( kg) ( m/s) 2 1 MeV J = MeV. Nuclear Binding Energy 00 (part 1 of ) 10.0 points A nuclear binding energy curve is shown below. The elements heavier than lead may undergo fission. The fission fragments lie near the highest point on the curve, each with a higher binding energy per nucleon. Similarly the light isotopes may fuse, the product nucleus also have a higher binding energy per nucleon. Both processes release energy.

2 Version 001 Nuclear tubman (IBII201516) 2 Average binding energy per nucleon (MeV) H 16 O Binding Energy per Nucleon 35 Cl He 6 Li 56 Fe 98 Mo 208 Pb 10 Ag12 I 159 Tb 19 Au 238 U Number of nucleons (A, mass number) Which process releases more energy per nucleon? 1. fission of uranium 2. fusion of hydrogen correct 3. Both must occur in the same process. More energy is released per nucleon when hydrogen nuclei fuse. Note the sharp increase in the binding energy curve between hydrogen and helium. 005 (part 2 of ) 10.0 points Which process releases the most energy? 1. fission of uranium correct 2. Both must occur in the same process. 3. fusion of hydrogen More total energy is release in fission, since there are many more nucleons in uranium than deuterium or tritium. 006 (part 3 of ) 10.0 points Which process would yield more energy? 1. fission of lead correct 2. fusion of lead 3. neither fusion or fission of lead Energy would be released if lead fissioned. Its products would have increased binding energy per nucleon. However, the likelihood of fission of lead is extremely remote. Fusion is energy forbidden, since the binding energy per nucleon of any heavier nucleus is lower. 00 (part of ) 10.0 points Which process would yield more energy? 1. fusion of iron 2. neither fusion or fission of iron correct 3. fission of iron Both fision and fusion of lead are energy forbidden, since the binding energy per nucleon of iron is at or near the highest of any nuclear isotope. AP B 1998 MC points A negative beta particle and a gamma ray are emitted during the radioactive decay of a nucleus of Pb. What will be the resulting nucleus? Hg Bi Tl Bi correct Po The beta decay will increase the proton number by 1 (with the negatively charged beta particle, or electron, keeping the total charge of the final decay products the same

3 Version 001 Nuclear tubman (IBII201516) 3 as the charge of the initial nucleus), while the total number of protons and neutrons remains unchanged. (Gamma rays, being high energy photons, carry neither electric charge nor nucleon number). Thus the resulting nucleus is 21 83Bi. AP B 1993 MC points Cobalt 60 is a radioactive source with a halflife of about 5 years. After how many years will the activity of a new sample of cobalt 60 be decreased to 1 8 its original value? Number of Undecayed Atoms N 0 Decay Plot 1. T = 5 years 2. It depends on the original amount of cobalt T = 15 years correct. T = 10 years 5. T = 2.5 years A B C D E F G H J Time Which of the lettered points on the time axis could represent the half-life of 1 C? 1. B correct 2. D 3. E. A 5. C After 5 years, the activity would be reduced to 1 2 its original value; after 10 years, 1 ; after 15 years, 1 8. AP B 1998 MC points The graph below shows the decay of a sample of 1 C that initially contained N 0 atoms. The half-life of an radioactive sample is the time it takes for half of the material to decay into something else. Initially, there were N 0 carbon 1 atoms. At time B, only N 0 2 atoms remained. The other half atoms had decayed. Therefore, the half-life of 1 C is represented by point B on the time axis.

4 Version 001 Nuclear tubman (IBII201516) Number of Undecayed Atoms N 0 N 0 2 Decay Plot A B C D E F G H J Time Holt SF 25B points Complete this radioactive decay F O 3. None of these. 12 Be B C correct 12 5 B?+ 0 1 e+ν The charge is conserved and the nucleon number is conserved. This is carbon: A = 12 0 = 12 Z = 5 ( 1) = B 12 6C+ 0 1 e+ν points Theisotope 56 26Fedecaysintotheisotope 56 2Co. By what process will this decay occur? 1. β correct 2. α 3. None of these. γ 5. β + The charge is conserved and the nucleon number is conserved. 0 1? = Fe 56 2Co +? A = = 0 Z = 26 2 = 1 1 e, so the decay is β which involves an electron and an antineutrino: Fe 2 Co+ 1 0 e+ν Holt SF 25C (part 1 of 2) 10.0 points The half-life of I is 8.0 days. Calculate the decay constant for this isotope. Correct answer: s 1. Let : T 1/2 = 8.0 d. λ = = T 1/2 8.0 d 1 d 1 h 2 h3600 s = s 1. Holt SF 25B (part 2 of 2) 10.0 points

5 Version 001 Nuclear tubman (IBII201516) 5 Whatistheactivityforasamplethatcontains iodine-131 nuclei? Correct answer: Ci. Let : N = activity = λn = ( s 1 )( ) 1 Ci s 1 = Ci. Holt SF 25Rev (part 1 of 2) 10.0 points Complete the nuclear reaction He 2. None of these H. 2He correct H? + 1 N 1 1 H+1 8 O The charge is conserved and the nucleon number is conserved He H 3. 8 Be. None of these 5. 2He correct 3Li+ 1 1H 2He+? 2? is helium: A = +1 = Z = = 2 3 Li+1 1 H 2 He+ 2 He Serway CP points How much time elapses before 8.% of the radioactivity of a sample of 2 33As disappears, as measured by its activity? The half-life of 2 33As is 26 hours. Correct answer: h. Let : R = 0.123R 0 and τ 1/2 = 26 h. 2? is helium: A = = Z = 1+8 = 2 2He+ 1 N 1 1H+ 1 8O 016 (part 2 of 2) 10.0 points Complete the nuclear reaction 3 Li+1 1 H 2 He +? R = R 0 e λt e λt = R R 0 ( ) R λt = ln R 0 t = ln R ( ) R τ 1/2 ln R 0 R 0 = λ ln2 (26 h) ln0.123 = = h. ln2

6 Version 001 Nuclear tubman (IBII201516) 6 Holt SF 25Rev points Findtheenergy released inthealphadecay of U,if Uhasanatomicmassof u, 23 90Th an atomic mass of u, and 2He an atomic mass of u. Correct answer:.265 MeV. Let : m U 238 = u, m Th 23 = u, m He = u, and c 2 = MeV/u U 23 90Th+ 2He m = m bound m unbound = m U 238 (m Th 23 +m He ) = u ( u u) = u The energy released is E bind = mc 2 = ( u)( MeV/u) =.265 MeV. Decay of Beta Rays points Consider the β-decay 12 N A Z X+β+ What is the value of Z (atomic number) and A (mass number)? 1. Z = ; A = Z =, A = Z = 6, A = 13. Z = 8, A = Z = 6, A = Z = 6, A = 1. Z = 6; A = 12 correct 8. Z = 8, A = 1 9. Z = ; A = Z = 8, A = 10 For β-decay, 12 N 12 8 X+β+ Concept 3 E points In what ways are fission and fusion reactions similar? 1. Both have critical masses. 2. Both involve the transformation of one or more elements into other elements. correct 3. Both need both heavy and light nuclei.. Both require high temperatures. Fission and fusion are alike in that both are energy-releasing nuclear reactions that involve transformation of one or more elements into other elements. However, they differ in important ways: Fission doesn t require high temperature; fusion does. Fission involves heavy nuclei; fusion involves light nuclei. As the names imply, fission is the splitting apart of a nucleus while fusion is the joining together of nuclei. The concept of critical mass applies to fission, but not fusion. Concept 3 E points Chemical burning is similar to nuclear fusion in many aspects.

7 Which statement is not correct? 1. In both the reaction is spread by heat from one region to neighboring regions. 2. Both require minimum ignition temperature to start. 3. Any amount of thermonuclear fuel or of combustible fuel can be stored.. Both have critical masses. correct Version 001 Nuclear tubman (IBII201516) Both chemical burning and nuclear fusion require a minimum ignition temperature to start and in both the reaction is spread by heat from one region to neighboring regions. There is no critical mass. Any amount of thermonuclear fuel or of combustible fuel can be stored.

Objectives 404 CHAPTER 9 RADIATION

Objectives 404 CHAPTER 9 RADIATION Objectives Explain the difference between isotopes of the same element. Describe the force that holds nucleons together. Explain the relationship between mass and energy according to Einstein s theory