Exam 29: Nuclear Physics

The half-life of cobalt-60 is 5.3 years,while that of strontium-90 is about 29 years.Suppose you have samples of both isotopes,and that they initially have the same activity (number of decays per second).What must be true of the numbers of cobalt-60 and strontium-90 nuclei in these samples?

When a neutron collides with a uranium-235 nucleus it can induce a variety of fission reactions.One such reaction is $^{235} _{92} U$ + ${}^{1}_{0}$ n → $^{140}_{54} Xe$ + ${}^{94}_{38}$ Sr + 2 ${}^{1}_{0}$ n The following mass values are known: $^{140}_{54} Xe$ : 139.921620 u ${}^{94}_{38}$ Sr: 93.915367 u $^{235} _{92} U$ : 235.043924 u ${}^{1}_{0}$ n: 1.008665 u What mass of uranium is needed to produce a 10-kiloton yield? (1 u = 931.5 MeV/c² = 1.66054 × 10^-27 kg,1-kiloton yield = 5.0 × 10¹² J)

Polonium-216 decays to lead-212 by emitting what kind of nuclear radiation?

The half-life of cobalt-60 is 5.3 years,while that of strontium-90 is about 29 years.Suppose you have samples of both isotopes,and that they initially contain equal numbers of atoms of these isotopes.How will the activities (number of decays per second)of the samples compare?

A 1.0-mol sample of an isotope is decaying with a half-life of 28 y.After 61 y,how many moles of this isotope are left and what is its activity in Bq?

Rutherfordium-261 has a half-life of 1.08 min.How long will it take for a sample of rutherfordium to lose one-third of its nuclei?

The atom ⁴⁰K decays radioactively to the gas ⁴⁰Ar.An ancient rock is found to contain enough ⁴⁰Ar gas to indicate that 77.0% of the ⁴⁰K in the rock has decayed to ⁴⁰Ar since the rock solidified.(Any previous argon would have boiled out of liquid rock.)How long ago did the rock solidify? The half-life of ⁴⁰K is 1.25 billion years.

Given that the half-life for radium-226 is 1600 y,how long is the "quarter-life" (that is,the time for the radiation to decay to one-fourth of its initial level)?

A gamma ray is also known as

The atom $^{223}_{87} Fr$ decays to ${}^{223}_{88}$ Ra by emitting what kind of nuclear radiation?

A radioactive sample has a half-life of 10 min.What fraction of the sample is left after 40 min?

When a neutron collides with a uranium-235 nucleus it can induce a variety of fission reactions.One such reaction is $^{235} _{92} U$ + ${}^{1}_{0}$ n → $^{140}_{54} Xe$ + ${}^{94}_{38}$ Sr + 2 ${}^{1}_{0}$ n The following mass values are known: $^{140}_{54} Xe$ : 139.921620 u ${}^{94}_{38}$ Sr: 93.915367 u $^{235} _{92} U$ : 235.043924 u ${}\\^{1}_{0}n$ : 1.008665 u How much energy is released in this reaction? (1 u = 931.5 MeV/c²)

When a β^- particle is emitted from an unstable nucleus,the atomic mass number of the nucleus

Suppose the half-life of an isotope is 2 days.You purchase 10 grams of the isotope,but it was produced in a laboratory 4 days before it was delivered to you.How much of this isotope will you have 3 days after it was delivered to you?

The symbol for a certain isotope of polonium is $^{214}_{84} Po$ .How many neutrons are there in the nucleus of this isotope?

An oxygen-15 nucleus, ${}^{15}_{8}$ O,decays to another atomic nucleus by emitting a β⁺ ray.What is the other atomic nucleus?

A hospital patient has been given a sample of ¹³¹I ,which has a half-life of 8.04 days.This sample is decaying at 5.9 times the acceptable level for exposure to the general public.How long must the patient wait for the decay rate of the sample to reach the acceptable level?

Plutonium has a half life of 2.4 × 10⁴ years.How long does it take for 99.0% of the plutonium to decay?

The half-life of radon-222 is 3.83 d.If a sample of radon initially contains 6.00 × 10⁸ radon atoms,how many of them are left after 10.0 d?

Two radioactive isotopes,X and Y,both decay to stable products.The half-life of X is about a day,while that of Y is about a week.Suppose a radioactive sample consists of a mixture of these two nuclides.If the mixture is such that the activities arising from X and Y are initially equal,then a few days later the activity of the sample will be due