CHEM 1010 - Chapter 5

Why doesn't uranium ore spontaneously undergo a chain reaction?

What property of half-lives makes radioactive material so problematic?

If a material has a half-life of 24 hours, how long do you have to wait until the amount of radioisotope is 1/4 its original amount?

Which of the following best describes an exothermic nuclear fission reaction?

Which of the following provides the minimum amount of protection you need to block the following form of radiation? (beta)

Alpha and beta rays are deflected in opposite directions in a magnetic field because

When food is irradiated with gamma rays from a cobalt-60 source, does the food become radioactive? Why?

If samples have the half-lives listed below, which is the most radioactive?

If uranium were to split into three segments of equal size instead of two, would more energy or less energy be released?

Ordinary hydrogen is sometimes called a perfect fuel, because of its almost unlimited supply on Earth, and when it burns, harmless water is the product of the combustion. So why don't we abandon fission energy and fusion energy, not to mention fossil-fuel energy, and just use hydrogen?

When 226Ra decays by emitting an alpha particle, what is the atomic number of the resulting nucleus? What is the resulting atomic mass?

What evidence supports the contention that the strong nuclear force is stronger than the electrical interaction at short inter-nuclear distances?

Explain how radioactive decay has always warmed the earth from the inside, and nuclear fusion has always warmed the earth from the outside.

Which of the following statements about fusion is true?

What is a half-life?

The strong nuclear force is very sensitive to

If carbon-14 is a beta emitter, what is the likely product of radioactive decay?

Which process would release energy from gold, fission or fusion? From carbon?

A sample of radium is usually a little warmer than its surroundings because

A shorter half-life means that a radioactive substance is relatively

Radioactivity is a tendency for an element or a material to

Which of the following statements best describes why a large nucleus is more likely to undergo radioactive decay?

The original reactor built in 1942 was just "barely" critical because the natural uranium that was used contained less than 1% of the fissionable isotope U-235 (half life 713 million years). What if, in 1942, the Earth had been 9 billion years old instead of 4.5 billion years old? Would this reactor have reached critical stage with natural uranium? Why?

How come an animal's carbon-14 levels do not start to decrease until it dies?

The isotope Cesium-137, which has a half-life of 30 years, is a product of nuclear power plants. How long will it take for this isotope to decay to about one-sixteenth its original amount?

Why does plutonium not occur in appreciable amounts in natural ore deposits?

Light nuclei can be split. For example, a deuteron, which is a proton-neutron combination, can split into a separate proton and separate neutron. Does such a process yield energy or cost energy? Why?

The age of the Dead Sea Scrolls was found by carbon-14 dating. Could this technique have worked if they were carved in stone tablets? Explain.

Just after an alpha particle leaves the nucleus, would you expect it to speed up? Why?

The alpha particle has twice the electric charge of the beta particle but deflects less than the beta in a magnetic field because it

What does Einstein's energy equation (E = mc2) say about the energy that is derived from nuclear fission reactions?

A friend produces a Geiger counter to check the local background radiation. It ticks. Another friend, who normally fears most that which is understood least, makes an effort to keep away from the region of the Geiger counter and looks to you for advice. What do you say?

Nuclear fission is known to occur

When 214Po emits a beta particle, it transforms into a new element. What are the atomic number and atomic mass of this new element?

From what process does the earth receive most of its energy?

What is the main technical difficulty in dealing with fusion reactions?

Why is the carbon-14 dating not accurate for estimating the age of materials more than 50,000 years old?

Is the mass of an atomic nucleus greater or less than the sum of the masses of the nucleons composing it? Why don't the nucleon masses add up to the total nuclear mass?

If samples have the half-lives listed below, which sample would remain radioactive the longest?

A neutron makes a better nuclear bullet than a proton or an electron because it

Elements above uranium in the periodic table do not exist in any appreciable amounts in nature because they have short half-lives. Yet there are several elements below uranium in atomic number with equally short half-lives that do exist in appreciable amounts in nature. How can you account for this? These are isotopes formed by living bodies.

Which of the following statements about fission is true?

What is a rem?

When the isotope bismuth-213 emits an alpha particle, what new element results?

Which type of radiation—alpha, beta, or gamma—results in the least change in atomic number?

A pair of protons in a small atomic nucleus repel each other, but they are also attracted to each other. Why?

Which of the following statements about chain reactions is true?

How is it possible for an element to decay "forward in the periodic table"--that is, to decay to an element of higher atomic number?

If a fusion reaction produces no appreciable radioactive isotopes, why does a hydrogen bomb produce significant radioactive fallout?

Radium-226 is a common isotope on Earth, but has a half-life of about 1600 years. Given that Earth is some 5 billions years old, why is there any radium at all?

Is it at all possible for a hydrogen nucleus to emit an alpha particle?

If a nucleus of 234Th absorbs a neutron and the resulting nucleus undergoes two successive beta decays (emitting electrons), what nucleus results?

Carbon-14 dating is fairly reliable for dating once-living materials that died up to

Which of the following statements regarding a nucleon is true?

How can a half-life be used to tell the age of a sample?

A certain radioactive element has a half-life of one hour. If you start with a 1-g sample of the element at noon, how much of this same element will be left at 3:00 PM?

Why is the combination of three protons and three neutrons stable, but the combination of three protons and one neutron is not?

The half-life of carbon-14 is 5,730 years. A sample is found to have one-eighth the original amount of carbon-14 in it. How old is the sample?

Which of the following elements is the most stable from a nuclear point of view?