Question 1

Two identical nuclei of mass 18 u are made to unite to make a single nucleus of mass 36 u.What is the radius of the result of this fusion?

Accepted Answer

A) 4.0 fm 
B) 6.3 fm 
C) 4.5 fm 
D) 7.2 fm 
A) 4.0 fm 
B) 6.3 fm 
C) 4.5 fm 
D) 7.2 fm A

Question 2

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

Accepted Answer

A) The daughter nucleus has more protons than the original nucleus. 
B) The daughter nucleus has more neutrons than the original nucleus. 
C) The daughter nucleus has the same number of nucleons as the original nucleus. 
D) The daughter nucleus has fewer protons than the original nucleus. 
E) The daughter nucleus has fewer neutrons than the original nucleus. 
A) The daughter nucleus has more protons than the original nucleus. 
B) The daughter nucleus has more neutrons than the original nucleus. 
C) The daughter nucleus has the same number of nucleons as the original nucleus. 
D) The daughter nucleus has fewer protons than the original nucleus. 
E) The daughter nucleus has fewer neutrons than the original nucleus. D,E

Question 3

A sphere made of a radioactive isotope initially has a mass of 6.88 kg.The half-life of this isotope is 1.34 h,and it decays by β- emission.At the end of 2.68 h,what is the mass of this sphere?

Accepted Answer

A) 6.88 kg 
B) 3.44 kg 
C) 1.72 kg 
D) 2.53 kg 
A) 6.88 kg 
B) 3.44 kg 
C) 1.72 kg 
D) 2.53 kg A

Question 4

Living matter has 1.3 × 10-10 % of its carbon in the form of 14C which has a half-life of 5730 y.A mammoth bone has a 300-g sample of carbon separated from it,and the sample is found to have an activity of 20 decays per second.How old is the bone?

Accepted Answer

A) 15,000 y 
B) 10,900 y 
C) 11,500 y 
D) 7600 y 
E) 6400 y 
A) 15,000 y 
B) 10,900 y 
C) 11,500 y 
D) 7600 y 
E) 6400 y

Question 5

What would be the expected radius of the nucleus of   Sr?

Accepted Answer

A) 4.0 fm 
B) 1.2 fm 
C) 5.4 fm 
D) 0.11 pm 
E) 0.54 pm 
A) 4.0 fm 
B) 1.2 fm 
C) 5.4 fm 
D) 0.11 pm 
E) 0.54 pm

Question 6

A certain isotope has a half-life of 32.4 hr and a relative biological effectiveness of 3.50.A sample of this isotope initially delivers an absorbed dose of 0.240 Gy to 250 g of tissue.
(a)What was the initial equivalent dose to the tissue in rem and in sieverts?
(b)How many joules of energy did the 250-g sample initially receive from the isotope?

Accepted Answer

(a)84 rem,

Question 7

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

Accepted Answer

A) The daughter nucleus has more protons than the original nucleus. 
B) The daughter nucleus has more neutrons than the original nucleus. 
C) The daughter nucleus has the same number of nucleons as the original nucleus. 
D) The daughter nucleus has fewer protons than the original nucleus. 
E) The daughter nucleus has fewer neutrons than the original nucleus. 
A) The daughter nucleus has more protons than the original nucleus. 
B) The daughter nucleus has more neutrons than the original nucleus. 
C) The daughter nucleus has the same number of nucleons as the original nucleus. 
D) The daughter nucleus has fewer protons than the original nucleus. 
E) The daughter nucleus has fewer neutrons than the original nucleus.

Question 8

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?

Accepted Answer

A) 1.02 min 
B) 1.62 min 
C) 0.632 min 
D) 2.70 min 
E) 3.24 min 
A) 1.02 min 
B) 1.62 min 
C) 0.632 min 
D) 2.70 min 
E) 3.24 min

Question 9

The radioactivity due to carbon-14 measured in a piece of a wood from an ancient site was found to produce 20 counts per minute from a given sample,whereas the same amount of carbon from a piece of living wood produced 160 counts per minute.The half-life of carbon-14,a beta emitter,is 5730 y.The age of the artifact is closest to

Accepted Answer

A) 5700 y. 
B) 12,000 y. 
C) 15,000 y. 
D) 17,000 y. 
E) 23,000 y. 
A) 5700 y. 
B) 12,000 y. 
C) 15,000 y. 
D) 17,000 y. 
E) 23,000 y.

Question 10

In a laboratory accident a work area is contaminated with radioactive material.Health physicists monitor the area during a 30-day period and,after correcting for the background rate,obtain the data shown in the table.   The accident occurred at t = 0.They determine that it will not be safe for workers to enter the area until the radioactivity level has dropped to 133 counts per minute.Of the choices listed below,which one is the earliest time that workers could safely return?

Accepted Answer

A) 38 days 
B) 44 days 
C) 50 days 
D) 32 days 
E) 24 days 
A) 38 days 
B) 44 days 
C) 50 days 
D) 32 days 
E) 24 days

Question 11

Today,the uranium found on Earth contains 0.720% 235U (with a half-life of 0.700 billion years)and 99.28% 238U (with a half-life of 4.50 billion years).At a time 2.20 billion years ago,what percent of the uranium on Earth was 238U (assuming that no other uranium isotopes were present)?

Accepted Answer

A) 95.6% 
B) 2.18% 
C) 6.29% 
D) 8.68% 
E) 4.53% 
A) 95.6% 
B) 2.18% 
C) 6.29% 
D) 8.68% 
E) 4.53%

Question 12

What would be the expected radius of a nucleus having 82 protons and 125 neutrons?

Accepted Answer

A) 5.2 fm 
B) 5.9 fm 
C) 6.0 fm 
D) 7.1 fm 
E) 17 fm 
A) 5.2 fm 
B) 5.9 fm 
C) 6.0 fm 
D) 7.1 fm 
E) 17 fm

Question 13

A radioisotope has a half-life of τ at a temperature of 150 K.If its temperature is increased to 300 K,what will its half-life be?

Accepted Answer

A) 4τ 
B) 2 τ 
C) τ 
D) τ/2 
E) τ/4 
A) 4τ 
B) 2 τ 
C) τ 
D) τ/2 
E) τ/4

Question 14

Consider two different isotopes of the same neutral element.Which statements about these isotopes are true? (There may be more than one correct choice.)

Accepted Answer

A) Both isotopes contain the same number of neutrons. 
B) Both isotopes contain the same number of protons. 
C) Both isotopes contain the same number of nucleons. 
D) Both isotopes contain the same number of orbital electrons. 
E) The sum of the protons and neutrons is the same for both isotopes. 
A) Both isotopes contain the same number of neutrons. 
B) Both isotopes contain the same number of protons. 
C) Both isotopes contain the same number of nucleons. 
D) Both isotopes contain the same number of orbital electrons. 
E) The sum of the protons and neutrons is the same for both isotopes.

Question 15

How much energy is released when 1.40 μg of 3H have decayed to 3He? The mass of 3He is 3.016029 u,the mass of 3H is 3.016049 u,and 1 u = 931.494 MeV/c2.

Accepted Answer

A) 830 J 
B) 11,900 J 
C) 7970 J 
D) 71,700 J 
E) 23,900 J 
A) 830 J 
B) 11,900 J 
C) 7970 J 
D) 71,700 J 
E) 23,900 J

Question 16

If a nucleus had a diameter of 8.0 fm,what would be its expected mass,in atomic mass units?

Accepted Answer

A) 7 u 
B) 296 u 
C) 37 u 
D) 64 u 
E) 128 u 
A) 7 u 
B) 296 u 
C) 37 u 
D) 64 u 
E) 128 u

Question 17

Which of the following statements about the atomic nucleus is correct? (There may be more than one correct choice.)

Accepted Answer

A) Large nuclei are denser than light nuclei. 
B) All nuclei have nearly the same density. 
C) The nucleus is held together more by the electrical force than by the gravitational force. 
D) A nucleus containing 20 nucleons will have approximately twice the radius as a nucleus containing 10 nucleons. 
E) As the number of nucleons increases the binding energy per nucleon always increases. 
A) Large nuclei are denser than light nuclei. 
B) All nuclei have nearly the same density. 
C) The nucleus is held together more by the electrical force than by the gravitational force. 
D) A nucleus containing 20 nucleons will have approximately twice the radius as a nucleus containing 10 nucleons. 
E) As the number of nucleons increases the binding energy per nucleon always increases.

Question 18

An ancient rock is found to contain 40Ar gas,indicating that   of the 40K in the rock has decayed since the rock solidified.Any argon would have boiled out of liquid rock.The half-life of 40K is 1.25 billion years.How long ago did the rock solidify?

Accepted Answer

A) 2.6 billion years 
B) 0.50 billion years 
C) 1.8 billion years 
D) 0.30 billion years 
A) 2.6 billion years 
B) 0.50 billion years 
C) 1.8 billion years 
D) 0.30 billion years

Question 19

Which of the following statements about the strong nuclear force are correct? (There may be more than one correct choice.)

Accepted Answer

A) It acts equally on protons and neutrons but not on electrons. 
B) It acts equally on protons,neutrons,and electrons. 
C) It has a much longer range than the electric force. 
D) It keeps electrons in their orbits around the nucleus. 
E) Because of its very short range,there is a limit to how large the nucleus can be. 
A) It acts equally on protons and neutrons but not on electrons. 
B) It acts equally on protons,neutrons,and electrons. 
C) It has a much longer range than the electric force. 
D) It keeps electrons in their orbits around the nucleus. 
E) Because of its very short range,there is a limit to how large the nucleus can be.

Question 20

The stability of   C 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   Be: 7.016928 u   B: 11.009305 u   C: 11.011433 u   N: 11.026742 u The   C nuclide is

Accepted Answer

A) not subject to alpha,β+,or β- decay. 
B) subject to alpha decay only. 
C) subject to β+ decay only. 
D) subject to β- decay only. 
E) subject to β+ or β- decay,but not to alpha decay. 
A) not subject to alpha,β+,or β- decay. 
B) subject to alpha decay only. 
C) subject to β+ decay only. 
D) subject to β- decay only. 
E) subject to β+ or β- decay,but not to alpha decay.

Exam 42: Nuclear Physics

Two identical nuclei of mass 18 u are made to unite to make a single nucleus of mass 36 u.What is the radius of the result of this fusion?

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

A sphere made of a radioactive isotope initially has a mass of 6.88 kg.The half-life of this isotope is 1.34 h,and it decays by β- emission.At the end of 2.68 h,what is the mass of this sphere?

Living matter has 1.3 × 10-10 % of its carbon in the form of 14C which has a half-life of 5730 y.A mammoth bone has a 300-g sample of carbon separated from it,and the sample is found to have an activity of 20 decays per second.How old is the bone?

What would be the expected radius of the nucleus of Sr?

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

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?

Today,the uranium found on Earth contains 0.720% 235U (with a half-life of 0.700 billion years)and 99.28% 238U (with a half-life of 4.50 billion years).At a time 2.20 billion years ago,what percent of the uranium on Earth was 238U (assuming that no other uranium isotopes were present)?

What would be the expected radius of a nucleus having 82 protons and 125 neutrons?

A radioisotope has a half-life of τ at a temperature of 150 K.If its temperature is increased to 300 K,what will its half-life be?

Consider two different isotopes of the same neutral element.Which statements about these isotopes are true? (There may be more than one correct choice.)

How much energy is released when 1.40 μg of 3H have decayed to 3He? The mass of 3He is 3.016029 u,the mass of 3H is 3.016049 u,and 1 u = 931.494 MeV/c2.

If a nucleus had a diameter of 8.0 fm,what would be its expected mass,in atomic mass units?

Which of the following statements about the atomic nucleus is correct? (There may be more than one correct choice.)

An ancient rock is found to contain 40Ar gas,indicating that of the 40K in the rock has decayed since the rock solidified.Any argon would have boiled out of liquid rock.The half-life of 40K is 1.25 billion years.How long ago did the rock solidify?

Which of the following statements about the strong nuclear force are correct? (There may be more than one correct choice.)

The stability of C 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 Be: 7.016928 u B: 11.009305 u C: 11.011433 u N: 11.026742 u The C nuclide is

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A sphere made of a radioactive isotope initially has a mass of 6.88 kg.The half-life of this isotope is 1.34 h,and it decays by β^- emission.At the end of 2.68 h,what is the mass of this sphere?

Living matter has 1.3 × 10^-10 % of its carbon in the form of ¹⁴C which has a half-life of 5730 y.A mammoth bone has a 300-g sample of carbon separated from it,and the sample is found to have an activity of 20 decays per second.How old is the bone?

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

Today,the uranium found on Earth contains 0.720% ²³⁵U (with a half-life of 0.700 billion years)and 99.28% ²³⁸U (with a half-life of 4.50 billion years).At a time 2.20 billion years ago,what percent of the uranium on Earth was ²³⁸U (assuming that no other uranium isotopes were present)?

How much energy is released when 1.40 μg of ³H have decayed to ³He? The mass of ³He is 3.016029 u,the mass of ³H is 3.016049 u,and 1 u = 931.494 MeV/c².

An ancient rock is found to contain ⁴⁰Ar gas,indicating that of the ⁴⁰K in the rock has decayed since the rock solidified.Any argon would have boiled out of liquid rock.The half-life of ⁴⁰K is 1.25 billion years.How long ago did the rock solidify?

The stability of C 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 Be: 7.016928 u B: 11.009305 u C: 11.011433 u N: 11.026742 u The C nuclide is