Question 1

A certain radioactive isotope decays to one fourth of its original amount in 4.0 hours.How long would it take for 20% of it to decay?

Accepted Answer

A) 0.40 hours 
B) 0.56 hours 
C) 0.64 hours 
D) 0.85 hours 
A) 0.40 hours 
B) 0.56 hours 
C) 0.64 hours 
D) 0.85 hours

Question 2

Consider the following fusion reaction   .The mass of   is 3.016029 u,the mass of   is 4.002602 u,and the mass of   is 7.0169298 u.Assuming that the Be atom is at rest after the reaction,calculate the minimum possible energy of the photon g that is released in this reaction.

Accepted Answer

A) 0.5 MeV 
B) 1 MeV 
C) 2 MeV 
D) 3 MeV 
E) 5 MeV 
A) 0.5 MeV 
B) 1 MeV 
C) 2 MeV 
D) 3 MeV 
E) 5 MeV

Question 3

3.25 mole of a radioactive isotope with a half-life of 18.2 hours sits on a countertop for 2.7 days exactly.How much of the isotope is left?

Accepted Answer

A) 0.14 mole 
B) 0.28 mole 
C) 1.34 mole 
D) 2.47 mole 
E) 3.25 mole 
A) 0.14 mole 
B) 0.28 mole 
C) 1.34 mole 
D) 2.47 mole 
E) 3.25 mole

Question 4

Assuming a neutron star is as dense as an atomic nucleus and there are 7.1 * 1056 nucleons (almost entirely neutrons),estimate the diameter of this neutron star.

Accepted Answer

A) 15 km 
B) 25 km 
C) 20 km 
D) 10 km 
E) 5 km 
A) 15 km 
B) 25 km 
C) 20 km 
D) 10 km 
E) 5 km

Question 5

Which isotope of carbon is the most stable?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 6

In a $\beta$- decay process,   .If A has mass 14.0032235 u and B has mass 14.0031592 u,what is the maximum energy of the emitted electron?

Accepted Answer

A) 0.26 keV 
B) 12.4 keV 
C) 59.9 keV 
D) 231keV 
E) 4186 keV 
A) 0.26 keV 
B) 12.4 keV 
C) 59.9 keV 
D) 231keV 
E) 4186 keV

Question 7

A certain radioactive isotope has a lifetime of 343.6 s.Suppose you have a beam made of radioactive ions of this isotope travelling at 5.21 * 107 m/s in the laboratory,circulating in a cyclotron.If you begin with a sample of 2.50 micro-moles of this isotope,how many atoms have you left after one hour?

Accepted Answer

A) 4.97 * 1013 
B) 4.23 * 1013 
C) 3.61 * 1013 
D) None are correct. 
A) 4.97 * 1013 
B) 4.23 * 1013 
C) 3.61 * 1013 
D) None are correct.

Question 8

A drug containing   with an activity of 2.00 $\mu$Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).The activity of the drug have at the preparation time (7:00 am)was 3.16 $\mu$Ci.What is the half-life of   ?

Accepted Answer

A) 6.05 hr 
B) 8.74 hr 
C) 12.6 hr 
D) 7.45 hr 
E) 6.91 hr 
A) 6.05 hr 
B) 8.74 hr 
C) 12.6 hr 
D) 7.45 hr 
E) 6.91 hr

Question 9

Element X decays to element Y via beta decay with a half-life of 0.77 s.Initially there is a sample of pure X and after 2.31 s there are 7 g of Y.What was the mass of the original sample?

Accepted Answer

A) 1 g 
B) 7 g 
C) 8 g 
D) 14 g 
E) 56 g 
A) 1 g 
B) 7 g 
C) 8 g 
D) 14 g 
E) 56 g

Question 10

A certain radioactive isotope has a half-life of 4.0 hours.How much time does it take for the amount of the isotope to decrease to one-eighth of its initial amount?

Accepted Answer

A) 12 hours 
B) 8.0 hours 
C) 64 hours 
D) 16 hours 
A) 12 hours 
B) 8.0 hours 
C) 64 hours 
D) 16 hours

Question 11

A drug containing   with an activity of 2.00 $\mu$Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).The activity of the drug have at the preparation time (7:00 am)was 3.16 $\mu$Ci.What is the decay constant of   ?

Accepted Answer

A) 0.165 hr-1 
B) 0.114 hr-1 
C) 0.0793 hr-1 
D) 0.204 hr-1 
E) 0.0961 hr-1 
A) 0.165 hr-1 
B) 0.114 hr-1 
C) 0.0793 hr-1 
D) 0.204 hr-1 
E) 0.0961 hr-1

Question 12

When carbon-14 undergoes a beta decay,an isotope of what element is produced?

Accepted Answer

A) beryllium 
B) boron 
C) carbon 
D) nitrogen 
E) oxygen 
A) beryllium 
B) boron 
C) carbon 
D) nitrogen 
E) oxygen

Question 13

A radioactive atom undergoes $\beta$- decay by emitting an electron and an anti-electron neutrino.When this occurs,what happens to the number of protons in the atom?

Accepted Answer

A) increases. 
B) decreases. 
C) remains constant. 
D) One can't determine what happens to the number of protons using only the information given. 
A) increases. 
B) decreases. 
C) remains constant. 
D) One can't determine what happens to the number of protons using only the information given.

Question 14

The half-life of a sample of 1011 atoms that decay by alpha emission is 10 minutes.How many alpha particles are emitted between the time interval 100 min and 200 min?

Accepted Answer

A) 9.8 * 107 
B) 9.8 * 104 
C) 2.0 * 106 
D) 1.0 * 107 
A) 9.8 * 107 
B) 9.8 * 104 
C) 2.0 * 106 
D) 1.0 * 107

Question 15

The Sun has a mass of 1.99 * 1030 kg and radiates energy at a rate of 3.85 *1026 W.What is the change in mass of the Sun during one day?

Accepted Answer

A) 1.6 * 1012 kg 
B) 2.2 * 1013 kg 
C) 8.7 * 1013 kg 
D) 3.7 * 1014 kg 
E) 1.1 * 1023 kg 
A) 1.6 * 1012 kg 
B) 2.2 * 1013 kg 
C) 8.7 * 1013 kg 
D) 3.7 * 1014 kg 
E) 1.1 * 1023 kg

Question 16

The nucleus of a radioactive atom captures one of the atom's innermost electrons.When this occurs,what happens to the mass number of the atom?

Accepted Answer

A) It increases. 
B) It decreases. 
C) It remains constant. 
D) One can't determine what happens to the atomic number using only the information given. 
A) It increases. 
B) It decreases. 
C) It remains constant. 
D) One can't determine what happens to the atomic number using only the information given.

Question 17

Calculate the binding energy of 7Li.(The mass of 7Li is 7.016004 u.)

Accepted Answer

A) 12.34 MeV 
B) 23.45 MeV 
C) 39.25 MeV 
D) 54.32 MeV 
E) 64.35 MeV 
A) 12.34 MeV 
B) 23.45 MeV 
C) 39.25 MeV 
D) 54.32 MeV 
E) 64.35 MeV

Exam 40: Nuclear Physics

A certain radioactive isotope decays to one fourth of its original amount in 4.0 hours.How long would it take for 20% of it to decay?

Consider the following fusion reaction .The mass of is 3.016029 u,the mass of is 4.002602 u,and the mass of is 7.0169298 u.Assuming that the Be atom is at rest after the reaction,calculate the minimum possible energy of the photon g that is released in this reaction.

3.25 mole of a radioactive isotope with a half-life of 18.2 hours sits on a countertop for 2.7 days exactly.How much of the isotope is left?

Assuming a neutron star is as dense as an atomic nucleus and there are 7.1 * 1056 nucleons (almost entirely neutrons),estimate the diameter of this neutron star.

Which isotope of carbon is the most stable?

In a β\betaβ - decay process, .If A has mass 14.0032235 u and B has mass 14.0031592 u,what is the maximum energy of the emitted electron?

A drug containing with an activity of 2.00 μ\muμ Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).The activity of the drug have at the preparation time (7:00 am)was 3.16 μ\muμ Ci.What is the half-life of ?

Element X decays to element Y via beta decay with a half-life of 0.77 s.Initially there is a sample of pure X and after 2.31 s there are 7 g of Y.What was the mass of the original sample?

A certain radioactive isotope has a half-life of 4.0 hours.How much time does it take for the amount of the isotope to decrease to one-eighth of its initial amount?

A drug containing with an activity of 2.00 μ\muμ Ci is to be injected into a patient at 11:00 am.A sample is prepared 4.00 hours before the injection (at 7:00 am).The activity of the drug have at the preparation time (7:00 am)was 3.16 μ\muμ Ci.What is the decay constant of ?

When carbon-14 undergoes a beta decay,an isotope of what element is produced?

A radioactive atom undergoes β\betaβ - decay by emitting an electron and an anti-electron neutrino.When this occurs,what happens to the number of protons in the atom?

The half-life of a sample of 1011 atoms that decay by alpha emission is 10 minutes.How many alpha particles are emitted between the time interval 100 min and 200 min?

The Sun has a mass of 1.99 * 1030 kg and radiates energy at a rate of 3.85 *1026 W.What is the change in mass of the Sun during one day?

The nucleus of a radioactive atom captures one of the atom's innermost electrons.When this occurs,what happens to the mass number of the atom?

Calculate the binding energy of 7Li.(The mass of 7Li is 7.016004 u.)

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Assuming a neutron star is as dense as an atomic nucleus and there are 7.1 * 10⁵⁶ nucleons (almost entirely neutrons),estimate the diameter of this neutron star.

In a $\beta$ ^- decay process, $In a \beta <sup>-</sup> decay process, .If A has mass 14.0032235 u and B has mass 14.0031592 u,what is the maximum energy of the emitted electron?$ .If A has mass 14.0032235 u and B has mass 14.0031592 u,what is the maximum energy of the emitted electron?

A radioactive atom undergoes $\beta$ ^- decay by emitting an electron and an anti-electron neutrino.When this occurs,what happens to the number of protons in the atom?

The half-life of a sample of 10¹¹ atoms that decay by alpha emission is 10 minutes.How many alpha particles are emitted between the time interval 100 min and 200 min?

The Sun has a mass of 1.99 * 10³⁰ kg and radiates energy at a rate of 3.85 *10²⁶ W.What is the change in mass of the Sun during one day?

Calculate the binding energy of ⁷Li.(The mass of ⁷Li is 7.016004 u.)