Question 1

$$\text { The half-life of arsenic-76 is } 26.7 \mathrm {~h} \text {. What are its (a) decay constant and (b) mean life? }$$

Accepted Answer

The answer of \[\text { The half-life of arsenic-76 is...

Question 2

When a $\beta ^ { + }$particle is emitted from an unstable nucleus, the atomic number of the nucleus

Accepted Answer

A)  decreases by 1 . 
B)  decreases by $2 .$ 
C)  increases by 1 . 
D)  increases by 2 . 
E)  does not change. 
A)  decreases by 1 . 
B)  decreases by $2 .$ 
C)  increases by 1 . 
D)  increases by 2 . 
E)  does not change.

Question 3

The half-life of radioactive iodine-137 is $8.0$ days. How many iodine nuclei are necessary to produce an activity of $1.0 \mu \mathrm { Ci }$ ? $\left( 1 \mathrm { Ci } = 3.70 \times 10 ^ { 10 } \mathrm {~Bq} \right)$

Accepted Answer

A)  $4.6 \times 10 ^ { 9 }$ 
B)  $3.7 \times 10 ^ { 10 }$ 
C)  $7.6 \times 10 ^ { 12 }$ 
D)  $2.9 \times 10 ^ { 9 }$ 
A)  $4.6 \times 10 ^ { 9 }$ 
B)  $3.7 \times 10 ^ { 10 }$ 
C)  $7.6 \times 10 ^ { 12 }$ 
D)  $2.9 \times 10 ^ { 9 }$

Question 4

A stable nucleus contains many protons very close to each other, all positively charged. Why do the protons not fly apart due to mutual Coulomb repulsion?

Accepted Answer

A)  An attractive nuclear force in the nucleus counteracts the effect of the Coulomb forces. 
B)  The neutrons in the nucleus shield the protons from each other. 
C)  The Coulomb force does not operate within nuclei. 
D)  The gravity of the protons and neutrons overcomes their repulsion at such close distances. 
E)  There are an equal number of electrons in the nucleus which neutralize the protons. 
A)  An attractive nuclear force in the nucleus counteracts the effect of the Coulomb forces. 
B)  The neutrons in the nucleus shield the protons from each other. 
C)  The Coulomb force does not operate within nuclei. 
D)  The gravity of the protons and neutrons overcomes their repulsion at such close distances. 
E)  There are an equal number of electrons in the nucleus which neutralize the protons.

Question 5

During $\beta$ - decay

Accepted Answer

A)  a proton is ejected from the nucleus. 
B)  the number of nucleons increases. 
C)  a neutron is transformed to a proton. 
D)  a proton is transformed to a neutron. 
E)  a neutron is ejected from the nucleus. 
A)  a proton is ejected from the nucleus. 
B)  the number of nucleons increases. 
C)  a neutron is transformed to a proton. 
D)  a proton is transformed to a neutron. 
E)  a neutron is ejected from the nucleus.

Question 6

What is the approximate nuclear radius of an isotope of sodium with 11 protons and 12
neutrons?

Accepted Answer

The answer of What is the approximate nuclear radius of...

Question 7

Americium-243 has a decay constant of $9.39 \times 10 ^ { - 5 }$ years $- 1$. How long will it take for a sample of americium-243 to lose one-third of its nuclei?

Accepted Answer

A)  $2960 \mathrm {~s}$ 
B)  $10.6 \times 10 ^ { 3 } \mathrm { y }$ 
C)  $7.84 \times 10 ^ { 3 } \mathrm { y }$ 
D)  $4.32 \times 10 ^ { 3 } \mathrm { y }$ 
E)  $6.44 \times 10 ^ { 3 } \mathrm { y }$ 
A)  $2960 \mathrm {~s}$ 
B)  $10.6 \times 10 ^ { 3 } \mathrm { y }$ 
C)  $7.84 \times 10 ^ { 3 } \mathrm { y }$ 
D)  $4.32 \times 10 ^ { 3 } \mathrm { y }$ 
E)  $6.44 \times 10 ^ { 3 } \mathrm { y }$

Question 8

A $1.0$-mol sample of an isotope is decaying with a half-life of $28 \mathrm { y }$. After $61 \mathrm { y }$, how man moles of this isotope are left and what is its activity in Bq?

Accepted Answer

The answer of A $1.0$-mol sample of an isotope is...

Question 9

When a stationary plutonium-239, ${ } _ { 94 } ^ { 239 } \mathrm { Pu }$, decays into uranium-235 plus an alpha particle, the energy released in the process is $5.24 \mathrm { MeV }$. The following masses are known:
${ } _ { 2 } ^ { 4 } \mathrm { He } : \quad 4.002603 \mathrm { u }$
${ } _ { 92 } ^ { 235 } \mathrm { U } : \quad 235.043924 \mathrm { u }$
What is the mass of the ${ } _ { 94 } ^ { 239 } \mathrm { Pu }$ nucleus, in amu? $\left( 1 \mathrm { u } = 931.494 \mathrm { MeV } / \mathrm { c } ^ { 2 } \right)$

Accepted Answer

A)  $239.00189 \mathrm { u }$ 
B)  $239.02775 \mathrm { u }$ 
C)  $238.98884 \mathrm { u }$ 
D)  $239.05215 \mathrm { u }$ 
E)  $238.99919 \mathrm { u }$ 
A)  $239.00189 \mathrm { u }$ 
B)  $239.02775 \mathrm { u }$ 
C)  $238.98884 \mathrm { u }$ 
D)  $239.05215 \mathrm { u }$ 
E)  $238.99919 \mathrm { u }$

Question 10

Neodymium ${ } _ { 60 } ^ { 144 } \mathrm { Nd }$ is an isotope that undergoes alpha decay. What isotope is the product of this decay?

Accepted Answer

A)  ${ } _ { 59 } ^ { 140 } \mathrm { Pr }$ 
B)  ${ } _ { 58 } ^ { 140 } \mathrm { Ce }$ 
C)  ${ } _ { 62 } ^ { 142 } \mathrm { Sm }$ 
D)  ${ } _ { 56 } ^ { 142 } \mathrm { Ba }$ 
E)  ${ } _ { 64 } ^ { 146 } \mathrm { Gd }$ 
A)  ${ } _ { 59 } ^ { 140 } \mathrm { Pr }$ 
B)  ${ } _ { 58 } ^ { 140 } \mathrm { Ce }$ 
C)  ${ } _ { 62 } ^ { 142 } \mathrm { Sm }$ 
D)  ${ } _ { 56 } ^ { 142 } \mathrm { Ba }$ 
E)  ${ } _ { 64 } ^ { 146 } \mathrm { Gd }$

Question 11

The atom ${ } _ { 87 } ^ { 223 } \mathrm { Fr }$ decays to ${ } _ { 88 } ^ { 223 } \mathrm { Ra }$ by emitting what kind of nuclear radiation?

Accepted Answer

A)  alpha 
B)  gamma 
C)  beta-plus 
D)  x-rays. 
E)  beta-minus 
A)  alpha 
B)  gamma 
C)  beta-plus 
D)  x-rays. 
E)  beta-minus

Question 12

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 mean life (time constant) of this sample?

Accepted Answer

The answer of The decay rate of a radioactive sample...

Question 13

The decay constant of a radioactive nuclide is $3.1 \times 10 ^ { - 3 } \mathrm {~s} ^ { - 1 }$. At a given instant, the activity of a specimen of the nuclide is $70 \mathrm { kBq }$. How much later has the activity declined to $10 \mathrm { kBq }$ ?

Accepted Answer

A)  $880 \mathrm {~s}$ 
B)  $690 \mathrm {~s}$ 
C)  $630 \mathrm {~s}$ 
D)  $750 \mathrm {~s}$ 
E)  $820 \mathrm {~s}$ 
A)  $880 \mathrm {~s}$ 
B)  $690 \mathrm {~s}$ 
C)  $630 \mathrm {~s}$ 
D)  $750 \mathrm {~s}$ 
E)  $820 \mathrm {~s}$

Question 14

A certain substance has a half-life of $5.0$ hours. How many nuclei of the substance are required to give an initial activity of $6.0 \mu \mathrm { Ci }$ ? $\left( 1 \mathrm { Ci } = 3.7 \times 10 ^ { 10 } \mathrm {~Bq} \right)$

Accepted Answer

A)  $5.8 \times 10 ^ { 9 }$ nuclei 
B)  $8.5 \times 10 ^ { 8 }$ nuclei 
C)  $3.2 \times 10 ^ { 9 }$ nuclei 
D)  $2.4 \times 10 ^ { 9 }$ nuclei 
E)  $6.3 \times 10 ^ { 8 }$ nuclei 
A)  $5.8 \times 10 ^ { 9 }$ nuclei 
B)  $8.5 \times 10 ^ { 8 }$ nuclei 
C)  $3.2 \times 10 ^ { 9 }$ nuclei 
D)  $2.4 \times 10 ^ { 9 }$ nuclei 
E)  $6.3 \times 10 ^ { 8 }$ nuclei

Question 15

Modern in-air nuclear bomb tests have created an extra high level of ${ } ^ { 14 } \mathrm { C }$ in our atmosphere. If future archaeologists date samples from this era, without knowing of this testing, will their carbon-14 dates be too young, too old, or correct? If correct, why?

Accepted Answer

A)  Too young. 
B)  Correct, since ${ } ^ { 14 } \mathrm { C }$ from bomb tests is different from that produced naturally. 
C)  Correct, because modern biological materials do not gather ${ } ^ { 14 } \mathrm { C }$ from bomb tests. 
D)  Too old. 
A)  Too young. 
B)  Correct, since ${ } ^ { 14 } \mathrm { C }$ from bomb tests is different from that produced naturally. 
C)  Correct, because modern biological materials do not gather ${ } ^ { 14 } \mathrm { C }$ from bomb tests. 
D)  Too old.

Question 16

The half-life of radon-222 is $3.83 \mathrm {~d}$. If a sample of radon initially contains $6.00 \times 10 ^ { 8 }$ radon atoms, how many of them are left after $10.0 \mathrm {~d}$ ?

Accepted Answer

A)  $7.29 \times 10 ^ { 8 }$ 
B)  $9.82 \times 10 ^ { 7 }$ 
C)  $7.67 \times 10 ^ { 7 }$ 
D)  $8.34 \times 10 ^ { 8 }$ 
E)  $8.56 \times 10 ^ { 8 }$ 
A)  $7.29 \times 10 ^ { 8 }$ 
B)  $9.82 \times 10 ^ { 7 }$ 
C)  $7.67 \times 10 ^ { 7 }$ 
D)  $8.34 \times 10 ^ { 8 }$ 
E)  $8.56 \times 10 ^ { 8 }$

Question 17

Carbon-14 decays by $\beta ^ { - }$emission. What nucleus is left after this decay?

Accepted Answer

A)  nitrogen-14 
B)  nitrogen-15 
C)  carbon-14 
D)  carbon-15 
E)  carbon-13 
A)  nitrogen-14 
B)  nitrogen-15 
C)  carbon-14 
D)  carbon-15 
E)  carbon-13

Question 18

Given that the half-life for radium-226 is 1600 y, how long is the "quarter-life" (that is, the
time for the radiation to decay to one-fourth of its initial level)?

Accepted Answer

The answer of Given that the half-life for radium-226 is...

Question 19

Name the first three isotopes of hydrogen, write their symbols in standard notation, and
indicate which one is the most common and which one is the most unstable.

Accepted Answer

@#LAT-DLM& is ordinary hydrogen, @#LAT-DLM& is deu

Question 20

$$\text { How many protons, neutrons, and nucleons are there in a carbon-14 nucleus? }$$

Accepted Answer

6 protons,

Exam 30: Nuclear Physics and Radioactivity

When a β+\beta ^ { + }β+ particle is emitted from an unstable nucleus, the atomic number of the nucleus

The half-life of radioactive iodine-137 is 8.08.08.0 days. How many iodine nuclei are necessary to produce an activity of 1.0μCi1.0 \mu \mathrm { Ci }1.0μCi ? (1Ci=3.70×1010 Bq)\left( 1 \mathrm { Ci } = 3.70 \times 10 ^ { 10 } \mathrm {~Bq} \right)(1Ci=3.70×1010 Bq)

A stable nucleus contains many protons very close to each other, all positively charged. Why do the protons not fly apart due to mutual Coulomb repulsion?

During β\betaβ - decay

What is the approximate nuclear radius of an isotope of sodium with 11 protons and 12 neutrons?

Americium-243 has a decay constant of 9.39×10−59.39 \times 10 ^ { - 5 }9.39×10−5 years −1- 1−1 . How long will it take for a sample of americium-243 to lose one-third of its nuclei?

A 1.01.01.0 -mol sample of an isotope is decaying with a half-life of 28y28 \mathrm { y }28y . After 61y61 \mathrm { y }61y , how man moles of this isotope are left and what is its activity in Bq?

Neodymium 60144Nd{ } _ { 60 } ^ { 144 } \mathrm { Nd }60144​Nd is an isotope that undergoes alpha decay. What isotope is the product of this decay?

The atom 87223Fr{ } _ { 87 } ^ { 223 } \mathrm { Fr }87223​Fr decays to 88223Ra{ } _ { 88 } ^ { 223 } \mathrm { Ra }88223​Ra by emitting what kind of nuclear radiation?

The decay rate of a radioactive sample decreases from 175kBq175 \mathrm { kBq }175kBq to 12.4kBq12.4 \mathrm { kBq }12.4kBq in 18.3 s18.3 \mathrm {~s}18.3 s . What is the mean life (time constant) of this sample?

A certain substance has a half-life of 5.05.05.0 hours. How many nuclei of the substance are required to give an initial activity of 6.0μCi6.0 \mu \mathrm { Ci }6.0μCi ? (1Ci=3.7×1010 Bq)\left( 1 \mathrm { Ci } = 3.7 \times 10 ^ { 10 } \mathrm {~Bq} \right)(1Ci=3.7×1010 Bq)

Modern in-air nuclear bomb tests have created an extra high level of 14C{ } ^ { 14 } \mathrm { C }14C in our atmosphere. If future archaeologists date samples from this era, without knowing of this testing, will their carbon-14 dates be too young, too old, or correct? If correct, why?

The half-life of radon-222 is 3.83 d3.83 \mathrm {~d}3.83 d . If a sample of radon initially contains 6.00×1086.00 \times 10 ^ { 8 }6.00×108 radon atoms, how many of them are left after 10.0 d10.0 \mathrm {~d}10.0 d ?

Carbon-14 decays by β−\beta ^ { - }β− emission. What nucleus is left after this decay?

Given that the half-life for radium-226 is 1600 y, how long is the "quarter-life" (that is, the time for the radiation to decay to one-fourth of its initial level)?

Name the first three isotopes of hydrogen, write their symbols in standard notation, and indicate which one is the most common and which one is the most unstable.

How many protons, neutrons, and nucleons are there in a carbon-14 nucleus? \text { How many protons, neutrons, and nucleons are there in a carbon-14 nucleus? } How many protons, neutrons, and nucleons are there in a carbon-14 nucleus?

Introduction, Measurement, Estimating

Describing Motion: Kinematics in One Dimension

Kinematics in Two Dimensions; Vectors

Dynamics: Newtons Laws of Motion

Circular Motion; Gravitation

Work and Energy

Linear Momentum

Rotational Motion

Static Equilibrium; Elasticity and Fracture

Fluids

Oscillations and Waves

Sound

Temperature and Kinetic Theory

Heat

The Laws of Thermodynamics

Electric Charge and Electric Field

Electric Potential

Electric Currents

Dc Circuits

Magnetism

Electromagnetic Induction and Faradays Law

Electromagnetic Waves

Light: Geometric Optics

The Wave Nature of Light

Optical Instruments

The Special Theory of Relativity

Early Quantum Theory and Models of the Atom

Quantum Mechanics of Atoms

Molecules and Solids

Nuclear Energy; Effects and Uses of Radiation

Elementary Particles

Astrophysics and Cosmology

Filters

When a $\beta ^ { + }$ particle is emitted from an unstable nucleus, the atomic number of the nucleus

The half-life of radioactive iodine-137 is $8.0$ days. How many iodine nuclei are necessary to produce an activity of $1.0 \mu \mathrm { Ci }$ ? $\left( 1 \mathrm { Ci } = 3.70 \times 10 ^ { 10 } \mathrm {~Bq} \right)$

During $\beta$ - decay

Americium-243 has a decay constant of $9.39 \times 10 ^ { - 5 }$ years $- 1$ . How long will it take for a sample of americium-243 to lose one-third of its nuclei?

A $1.0$ -mol sample of an isotope is decaying with a half-life of $28 \mathrm { y }$ . After $61 \mathrm { y }$ , how man moles of this isotope are left and what is its activity in Bq?

Neodymium ${ } _ { 60 } ^ { 144 } \mathrm { Nd }$ is an isotope that undergoes alpha decay. What isotope is the product of this decay?

The atom ${ } _ { 87 } ^ { 223 } \mathrm { Fr }$ decays to ${ } _ { 88 } ^ { 223 } \mathrm { Ra }$ by emitting what kind of nuclear radiation?

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 mean life (time constant) of this sample?

A certain substance has a half-life of $5.0$ hours. How many nuclei of the substance are required to give an initial activity of $6.0 \mu \mathrm { Ci }$ ? $\left( 1 \mathrm { Ci } = 3.7 \times 10 ^ { 10 } \mathrm {~Bq} \right)$

Modern in-air nuclear bomb tests have created an extra high level of ${ } ^ { 14 } \mathrm { C }$ in our atmosphere. If future archaeologists date samples from this era, without knowing of this testing, will their carbon-14 dates be too young, too old, or correct? If correct, why?

The half-life of radon-222 is $3.83 \mathrm {~d}$ . If a sample of radon initially contains $6.00 \times 10 ^ { 8 }$ radon atoms, how many of them are left after $10.0 \mathrm {~d}$ ?

Carbon-14 decays by $\beta ^ { - }$ emission. What nucleus is left after this decay?

$\text { How many protons, neutrons, and nucleons are there in a carbon-14 nucleus? }$