Quantum Physics

Problems 96924. A building has become accidentally contaminated 31. Determine which of the following suggested decayswith radioactivity. The longest-lived material in can occur spontaneously:the building is strontium-90. (The atomic mass of9038 Sr 40is 89.907 7.) If the building initially contained (a) : e 40144 4 14020 Ca 19 K ; (b) 60 Nd : 2 He 58 Ce5.0 kg of this substance, and the safe level is less6632. (mass 65.929 1 u) undergoes beta decaythan 10.0 counts/min, how long will the building28 Ni 66to (mass 65.9289 u). (a) Write the completebe unsafe?29 Cudecay formula for this process. (b) Find the maximumkinetic energy of the emerging electrons.Section 29.4 The Decay Processes25. Complete the following radioactive decay formulas:21283 Bi : ? 4 2 He95 Kr : ? e 3626. Complete the following radioactive decay formulas:23423090 Th : 88 Ra ?? : 14 7 N e 27. Complete the following radioactive decay formulas:9444 Ru : 4 2 He ?140Nd : ? 58 Ce14460? : 4 2 He 140 58 Ce125 B : ? e ? : e 4019 K28. Figure P29.28 shows the steps by which 92 U decays207to . Enter the correct isotope symbol in eachsquare.235 U 9282 Pb 235e – e – e – e – e – e –33. An 3 H nucleus beta decays into 3 He by creatingan electron and an antineutrino according to thereaction31 H3: 2 He e Use Appendix B to determine the total energy releasedin this reaction.34. A piece of charcoal used for cooking is found at theremains of an ancient campsite. A 1.00-kg sample ofcarbon from the wood has an activity of 2.00 10 3decays per minute. Find the age of the charcoal.[Hint: Living material has an activity of 15.0 decays/minuteper gram of carbon present.]35. A wooden artifact is found in an ancient tomb. Its carbon-14( 6 C) activity is measured to be 60.0% of that14in a fresh sample of wood from the same region. Assumingthe same amount of 14 C was initially presentin the wood from which the artifact was made, determinethe age of the artifact.36. A living specimen in equilibrium with the atmospherecontains one atom of 14 C (half-life 5 730 yr)for every 7.70 10 11 stable carbon atoms. An archeologicalsample of wood (cellulose, C 12 H 22 O 11 )contains 21.0 mg of carbon. When the sample isplaced inside a shielded beta counter with 88.0%counting efficiency, 837 counts are accumulated inone week. Assuming that the cosmic-ray flux and theEarth’s atmosphere have not changed appreciablysince the sample was formed, find the age of thesample.Figure P29.28e – e –20782 Pb29.The mass of 56 Fe is 55.934 9 u andthe mass of 56 Co is 55.939 9 u. Which isotope decaysinto the other and by what process?23830. Find the energy released in the alpha decay of 92 U .234The following mass value will be useful: 90Th has amass of 234.043 583 u.Section 29.6 Nuclear Reactions37. The first known reaction in which the product nucleuswas radioactive (achieved in 1934) was one27in which 13 Al was bombarded with alpha particles.Produced in the reaction were a neutron and aproduct nucleus. (a) What was the product nucleus?(b) Find the Q value of the reaction.38. Complete the following nuclear reactions:? 14 7 N : 1 1 H 17 8 O73 Li 1 1 H : 4 2 He ?