Exam 42: Nuclear Physics

An archaeologist finds the ¹⁴C in a sample of of material to be decaying at 107 counts per second.A modern 1.00-g sample of the same material decays at 151 counts per second.The half-life of ¹⁴C is 5730 y.How old is the sample?

How many days are required for a radioactive sample,with a half-life of 5.7 d and an initial activity of 1.07 × 10⁵ Bq,to decay to an activity of 100 Bq?

Fermium-253 has a half-life of 3.00 d.A sample of fermium contains 7.37 × 10⁷ nuclei.How long will it take for there to be only 3.36 × 10⁶ fermium nuclei in this sample?

The following masses are known: n (neutron)1.008665 u H 1.007825 u Fe 56.935399 u What is the binding energy of Fe,in MeV? (1 u = 1.6605 × 10^-27 kg = 931.5 MeV/c²)

The stability of Sc with respect to alpha,β⁺,and β^- decay is to be determined.Do not consider the possibility of decay by electron capture.The following atomic masses are known: He: 4.002603 u K: 42.960717 u Ca: 46.954543 u Sc 46.952409 u Ti: 46.951764 u The Sc nuclide is

A stationary plutonium-239 nucleus decays into a uranium-235 nucleus plus an alpha particle.The energy released in the process is 5.24 MeV.Given the following mass values He: 4.002603 u U: 235.043924 u what is the kinetic energy of the U nucleus? (1 u =931.494 MeV/c²)

The set of nuclear reactions that power our sun can be summarized a 4p⁺ → ⁴He⁺² + 2e⁺.The masses of the particles involved are 938.272 MeV/c² (proton,p⁺),3727.38 MeV/c² (alpha particle,⁴He⁺²),and 0.511 MeV/c² (positron,e⁺).How much energy is released by each set of these reactions?

Uranium-238 decays into thorium-234 plus an alpha particle.How much energy is released in this process? 1 u = 931.494 MeV/c²,and the relevant mass values are He: 4.002603 u Th: 234.043583 u U: 238.050786 u

The stability of Fe with respect to alpha,β⁺,and β^- decay is to be determined.Do not consider the possibility of decay by electron capture.The following atomic masses are known: He: 4.002603 u Cr: 51.944768 u Mn: 55.938907 u Fe: 55.934939 u Co: 55.939841 u The Fe nuclide is

Carbon-14 has a half-life of 5730 y.A sample of wood has been recovered by an archaeologist.The sample is sent to a laboratory,where it is determined that the activity of the sample is 0.144 Bq/g.By comparing this activity with the activity of living organic matter, 0.230 Bq/g,the scientist determines how old the wood sample is,or more precisely,when the tree that the sample came from died.How old is the sample of wood?

A certain nucleus containing 8 protons and 7 neutrons has a density ρ.Which of the following values would be closest to the expected value of the density of a nucleus having 51 protons and 69 neutrons?

The carbon in your body was formed in nuclear reactions in long-dead stars.How much energy was released when three ⁴He nuclei combined to make ¹²C? The mass of ⁴He is 4.002603 u,the mass of ¹²C is 12.0000 u,and 1 u = 931.494 MeV/c².

A radioactive nuclide of atomic number Z emits an electron,then the daughter nuclide emits a gamma ray.What is the atomic number of the resulting nuclide after both processes?

What is the binding energy per nucleon for Al? The neutral Al atom has a mass of 26.981539 u; a neutral hydrogen atom has a mass of 1.007825 u; a neutron has a mass of 1.008665 u; and a proton has a mass of 1.007277 u.(1 u = 931.494 MeV/c²)

Heavier stable nuclei tend to have

If a nucleus decays by gamma decay to a daughter nucleus,which of the following statements about this decay are correct? (There may be more than one correct choice.)

The material used in certain nuclear bombs is ²³⁹Pu,which has a half-life of about 20,000 years.How long must we wait for a buried stockpile of this substance to decay to 4.0% of its original ²³⁹Pu mass?

An air sample is contaminated with ¹⁵O,which has a half-life of 2.03 min.One possible way to minimize its hazard is to pass it through a long pipe to allow it to decay inside the pipe until it can be safely released into the atmosphere.If the oxygen moves at a speed of 1.1 m/s in the pipe,how long must the pipe be for the sample to have decayed to 3.0% of its original activity just as it leaves the pipe?

Going from medium mass nuclei to heavy nuclei,the average binding energy per nucleon