Exam 30: Nuclear Physics and Radioactivity

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?

The carbon in our bodies was formed in nuclear reactions in long-dead stars. How much energy was released when the right number of 4 He nuclei combined to make $12 \mathrm { C }$ ? The mass of $4 \mathrm { He }$ is $3728.40 \mathrm { MeV } / \mathrm { c } 2$ and the mass of $12 \mathrm { C }$ is $11,177.93 \mathrm { MeV } / \mathrm { c } 2$ .

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

A sodium-22 nucleus, ${ } _ { 11 } ^ { 22 } \mathrm { Na }$ , decays into a neon-22 nucleus, ${ } _ { 10 } ^ { 22 } \mathrm { Ne }$ , and one other particle. What is the other particle?

The two strongest forces that act between protons in a nucleus are

A fusion reaction releases energy because the binding energy of the resulting nucleus

The binding energy per nucleon of a nucleus

All nuclei of a given element have the same number of

What happens to the half-life of a radioactive substance as it decays?

In $\beta ^ { - }$ decay, the number of neutrons in the nucleus is

Estimate the radius (in fm) of a radon nucleus that contains 86 protons and 136 neutrons.

What mass of $14 \mathrm { C }$ , with a half-life of $5730 \mathrm { y }$ , do you need to provide a decay rate of $280.0 \mathrm {~Bq}$ ? The mass of ${ } ^ { 14 } \mathrm { C }$ is $14.00 \mathrm { u }$ , and $1 \mathrm { u } = 1.6605 \times 10 ^ { - 27 } \mathrm {~kg}$ .

The decay rate of a radioactive sample decreases from $175 \mathrm { kBq }$ to $12.4 \mathrm { kBq }$ in $18.3 \mathrm {~s}$ . What is the decay constant of this sample?

An archaeologist finds the 14C in a sample of 2.10 g of material to be decaying at 107 Bq. A modern 1.00-g sample of the same material decays at 151 Bq,and assume this rate has also held in The past. The half-life of 14C is 5730 years. How old is the sample?

In $\beta$ - decay, the number of protons in the nucleus is

A carbon-14 nucleus decays to a nitrogen-14 nucleus by beta-minus decay. How much energy (in MeV) is released if carbon-14 has a mass of $14.003242 \mathrm { u }$ and nitrogen-14 has a mass of $14.003074 \mathrm { u }$ ? $\left( 1 \mathrm { u } = 931.5 \mathrm { MeV } / \mathrm { c } ^ { 2 } \right)$

In a ${ } _ { 41 } ^ { 93 } \mathrm { Nb }$ nucleus, how many protons, neutrons, and electrons are found there?

In massive stars, three helium nuclei fuse together, forming a carbon nucleus, and this reaction heats the core of the star. The net mass of the three helium nuclei must therefore be

A gamma ray is also known as

The half-life of tritium is 12.3 y. What is its mean life (time constant)?