Question 1

Cobalt-60 is a beta emitter with a half-life of 5.3 years. Approximately what fraction of cobalt-60 atoms will remain in a particular sample after 26.5 years?

Accepted Answer

A) 1/5 
B) 1/16 
C) 1/26 
D) 1/32 
E) 1/64 
A) 1/5 
B) 1/16 
C) 1/26 
D) 1/32 
E) 1/64

Question 2

Radium-226 decays by alpha emission. What is its decay product?

Accepted Answer

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

Question 3

The radioisotope potassium-40 decays to argon-40 by positron emission with a half-life of 1.3 * 109 yr. A sample of moon rock was found to contain 78 argon-40 atoms for every 22 potassium-40 atoms. The age of the rock is

Accepted Answer

A) 8.1* 10-10 yr. 
B) 2.4 * 109 yr. 
C) 2.8 * 109 yr. 
D) 4.6 * 109 yr. 
E) 6.8 * 109 yr. 
A) 8.1* 10-10 yr. 
B) 2.4 * 109 yr. 
C) 2.8 * 109 yr. 
D) 4.6 * 109 yr. 
E) 6.8 * 109 yr.

Question 4

Present-day plant life has a carbon-14 decay rate of 16 disintegrations per minute (dpm)per gram of carbon. If a contemporary wooden chair were somehow preserved for the next 3,900 years, what 14C decay rate should be expected from the wood used to make the chair? (t1/2 = 5,730 yr)

Accepted Answer

A) 26 dpm 
B) 12 dpm 
C) 11 dpm 
D) 10 dpm 
E) 8 dpm 
A) 26 dpm 
B) 12 dpm 
C) 11 dpm 
D) 10 dpm 
E) 8 dpm

Question 5

Balance the equation   .

Accepted Answer

The answer of Balance the equation   ....

Question 6

Charcoal found under a stone at Stonehenge, England, has a carbon-14 activity that is 0.60 that of new wood. How old is the charcoal? (The half-life of carbon-14 is 5,730 years.)

Accepted Answer

A) Less than 5,730 yr 
B) Between 5,730 and 11,460 yr 
C) Between 11,460 and 17,190 yr 
D) More than 17,190 yr 
A) Less than 5,730 yr 
B) Between 5,730 and 11,460 yr 
C) Between 11,460 and 17,190 yr 
D) More than 17,190 yr

Question 7

Compare nuclear reactions with chemical reactions in terms of the conservation of mass.

Accepted Answer

As opposed to chemical reactio

Question 8

Predict which nucleus is less stable,   or   .

Accepted Answer

The answer of Predict which nucleus is less stable, ...

Question 9

In the following reaction, identify X.

Accepted Answer

A) 7$\beta$ 
B) 3$\alpha$ 
C) 4n 
D)    
E) 15p 
A) 7$\beta$ 
B) 3$\alpha$ 
C) 4n 
D)    
E) 15p

Question 10

Tritium is a radioisotope of hydrogen having a half-life of 12.3 years. If you initially had 1.0 * 10-7 mole of tritium, calculate the decay rate of the sample.

Accepted Answer

1.08 * 10<

Question 11

As a result of beta decay, the product nucleus is

Accepted Answer

A) one atomic number lower than the original element. 
B) two atomic numbers higher than the original element. 
C) one atomic number higher than the original element. 
D) two atomic numbers lower than the original element. 
E) four atomic numbers lower than the original element. 
A) one atomic number lower than the original element. 
B) two atomic numbers higher than the original element. 
C) one atomic number higher than the original element. 
D) two atomic numbers lower than the original element. 
E) four atomic numbers lower than the original element.

Question 12

Determine how much energy is released when polonium-210 decays according to   . [Atomic masses: polonium-210 = 209.982857 amu; helium-4 = 4.002603 amu; lead-206 = 205.974449 amu]

Accepted Answer

A) 4.14 * 109 kJ/mol 
B) 7.20 * 1011 kJ/mol 
C) 5.22 * 108 kJ/mol 
D) 4.66 * 109 kJ/mol 
E) 6.43 * 1012 kJ/mol 
A) 4.14 * 109 kJ/mol 
B) 7.20 * 1011 kJ/mol 
C) 5.22 * 108 kJ/mol 
D) 4.66 * 109 kJ/mol 
E) 6.43 * 1012 kJ/mol

Question 13

Describe the role of a moderator in a fission reactor, and give examples of two substances that are used as moderators.

Accepted Answer

Moderators slow the neutrons a

Question 14

Naturally occurring uranium contains approximately 1% U-235 and 99% U-238. Of these, the isotope that undergoes fission in a nuclear reactor is U-238.

Accepted Answer

A) True 
 B)False

Question 15

Which type of nuclear process requires an extremely high temperature (millions of degrees)?

Accepted Answer

A) beta decay 
B) fission reaction 
C) fusion reaction 
D) alpha decay 
E) positron emission 
A) beta decay 
B) fission reaction 
C) fusion reaction 
D) alpha decay 
E) positron emission

Question 16

Carbon-11 is a radioactive isotope of carbon. Its half-life is 20.3 minutes. What fraction of the initial number of carbon-11 atoms in a sample will remain after 81 minutes?

Accepted Answer

A) 1/16 
B) 1/4 
C) 1/2 
D) 1/32 
E) 1/8 
A) 1/16 
B) 1/4 
C) 1/2 
D) 1/32 
E) 1/8

Question 17

The carbon-14 activity of some ancient Indian corn was found to be 7.0 disintegrations per minute (dpm)per gram of carbon. If present-day plant life has 16 dpm per gram of carbon, how old is the Indian corn? (t1/2 = 5,730 yr)

Accepted Answer

A) 6,800 yr 
B) 2,500 yr 
C) 4,700 yr 
D) 10,000 yr 
E) 7,200 yr 
A) 6,800 yr 
B) 2,500 yr 
C) 4,700 yr 
D) 10,000 yr 
E) 7,200 yr

Question 18

A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. Approximately how many U-238 atoms were in the rock when it was formed billions of years ago? (The half life for 238U ?$\rarr$ 206Pb is 4.5 * 109 yr.)

Accepted Answer

A) 1.32 atoms 
B) 5.8 * 10-6 atoms 
C) 2.4 * 1018 atoms 
D) 3.5 * 1018 atoms 
E) 3.5 * 1021 atoms 
A) 1.32 atoms 
B) 5.8 * 10-6 atoms 
C) 2.4 * 1018 atoms 
D) 3.5 * 1018 atoms 
E) 3.5 * 1021 atoms

Question 19

How many neutrons and protons (nucleons)does an atom with the symbol   have?

Accepted Answer

A) 33 
B) 16 
C) 49 
D) None of the above. 
A) 33 
B) 16 
C) 49 
D) None of the above.

Question 20

Balance the equation   .

Accepted Answer

The answer of Balance the equation   ....

Exam 21: Nuclear Chemistry

Cobalt-60 is a beta emitter with a half-life of 5.3 years. Approximately what fraction of cobalt-60 atoms will remain in a particular sample after 26.5 years?

Radium-226 decays by alpha emission. What is its decay product?

The radioisotope potassium-40 decays to argon-40 by positron emission with a half-life of 1.3 * 109 yr. A sample of moon rock was found to contain 78 argon-40 atoms for every 22 potassium-40 atoms. The age of the rock is

Present-day plant life has a carbon-14 decay rate of 16 disintegrations per minute (dpm)per gram of carbon. If a contemporary wooden chair were somehow preserved for the next 3,900 years, what 14C decay rate should be expected from the wood used to make the chair? (t1/2 = 5,730 yr)

Balance the equation .

Charcoal found under a stone at Stonehenge, England, has a carbon-14 activity that is 0.60 that of new wood. How old is the charcoal? (The half-life of carbon-14 is 5,730 years.)

Compare nuclear reactions with chemical reactions in terms of the conservation of mass.

Predict which nucleus is less stable, or .

In the following reaction, identify X.

Tritium is a radioisotope of hydrogen having a half-life of 12.3 years. If you initially had 1.0 * 10-7 mole of tritium, calculate the decay rate of the sample.

As a result of beta decay, the product nucleus is

Determine how much energy is released when polonium-210 decays according to . [Atomic masses: polonium-210 = 209.982857 amu; helium-4 = 4.002603 amu; lead-206 = 205.974449 amu]

Describe the role of a moderator in a fission reactor, and give examples of two substances that are used as moderators.

Naturally occurring uranium contains approximately 1% U-235 and 99% U-238. Of these, the isotope that undergoes fission in a nuclear reactor is U-238.

Which type of nuclear process requires an extremely high temperature (millions of degrees)?

Carbon-11 is a radioactive isotope of carbon. Its half-life is 20.3 minutes. What fraction of the initial number of carbon-11 atoms in a sample will remain after 81 minutes?

The carbon-14 activity of some ancient Indian corn was found to be 7.0 disintegrations per minute (dpm)per gram of carbon. If present-day plant life has 16 dpm per gram of carbon, how old is the Indian corn? (t1/2 = 5,730 yr)

A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. Approximately how many U-238 atoms were in the rock when it was formed billions of years ago? (The half life for 238U ? →\rarr→ 206Pb is 4.5 * 109 yr.)

How many neutrons and protons (nucleons)does an atom with the symbol have?

Balance the equation .

Introduction

Atoms, Molecules, and Ions

Stoichiometry

Reactions in Aqueous Solution

Gases

Energy Relationships in Chemical Reactions

The Electronic Structure of Atoms

The Periodic Table

Chemical Bonding I: the Covalent Bond

Chemical Bonding Ii: Molecular Geometry and Hybridization of Atomic Orbitals

Introduction to Organic Chemistry

Intermolecular Forces and Liquids and Solids

Physical Properties of Solutions

Chemical Kinetics

Chemical Equilibrium

Acids and Bases

Acid-Base Equilibria and Solubility Equilibria

Thermodynamics

Redox Reactions and Electrochemistry

The Chemistry of Coordination Compounds

Organic Polymerssynthetic and Natural

Filters

The radioisotope potassium-40 decays to argon-40 by positron emission with a half-life of 1.3 * 10⁹ yr. A sample of moon rock was found to contain 78 argon-40 atoms for every 22 potassium-40 atoms. The age of the rock is

Present-day plant life has a carbon-14 decay rate of 16 disintegrations per minute (dpm)per gram of carbon. If a contemporary wooden chair were somehow preserved for the next 3,900 years, what ¹⁴C decay rate should be expected from the wood used to make the chair? (t_1/2= 5,730 yr)

Tritium is a radioisotope of hydrogen having a half-life of 12.3 years. If you initially had 1.0 * 10^-7 mole of tritium, calculate the decay rate of the sample.

The carbon-14 activity of some ancient Indian corn was found to be 7.0 disintegrations per minute (dpm)per gram of carbon. If present-day plant life has 16 dpm per gram of carbon, how old is the Indian corn? (t_1/2 = 5,730 yr)

A rock contains 0.37 mg of Pb-206 and 0.95 mg of U-238. Approximately how many U-238 atoms were in the rock when it was formed billions of years ago? (The half life for ²³⁸U ? $\rarr$ ²⁰⁶Pb is 4.5 * 10⁹ yr.)