Deck 31: Nuclear Physics and Radioactivity

Question 1

Which of the following is not an assumption involved in the expression: r = (1.2 × 10^-15 m)A^1/3?

A)Nuclei are incompressible.
B)The nucleus is spherical in shape.
C)All nucleons have roughly the same mass.
D)Nuclear densities are proportional to the mass numbers.
E)The number of nucleons is proportional to the nuclear mass.

Answer 1

Nuclear densities are proportional to the mass numbers.

Question 2

What is the approximate radius of a nitrogen nucleus that has seven protons and seven neutrons?

A)1.2 × 10^-15 m
B)2.2 × 10^-15 m
C)2.7 × 10^-15 m
D)2.9 × 10^-15 m
E)3.2 × 10^-15 m

Answer 2

2.9 × 10^-15 m

Question 3

The half-life a particular isotope of barium is 12 s.What is the activity of a 1.0 × 10^-6 kg sample of this isotope?

A)1.2 × 10¹⁵ Bq
B)1.8 × 10¹⁶ Bq
C)2.5 × 10¹⁷ Bq
D)3.6 × 10¹⁸ Bq
E)6.0 × 10²³ Bq

Answer 3

2.5 × 10¹⁷ Bq

Question 4

What is the SI unit for activity?

A)Ci
B)counts/min
C)Hz
D)Gy
E)Bq

Question 5

Which one of the following descriptive terms does not apply to nuclear forces?

A)strong
B)charge-independent
C)weak
D)short-range
E)long-range

Question 6

This question refers to the figure shown.Which one of the following concepts explains why heavy nuclei do not follow the N = Z line (or trend) in the figure?

A)transmutation
B)Coulomb repulsion
C)particle-wave duality
D)Pauli exclusion principle
E)Heisenberg uncertainty principle

Question 7

Which one of the following quantities is not a conserved quantity according to the laws of physics?

A)electric charge
B)nucleon number
C)angular momentum
D)linear momentum
E)kinetic energy

Question 8

How many neutrons are there in the nucleus ?

A)79
B)55
C)134
D)24
E)120

Question 9

The half-life of a particular isotope of iodine is 8.0 days.How much of a 10.0-g sample of this isotope will remain after 30 days?

A)0.37 g
B)0.45 g
C)0.60 g
D)0.74 g
E)1.25 g

Question 10

An isotope of krypton has a half-life of 3 minutes.A sample of this isotope produces 1000 counts per minute in a Geiger counter.Determine the number of counts per minute produced after 15 minutes.

A)zero
B)15
C)30
D)60
E)1000

Question 11

Which one of the following statements concerning stable nuclei is true?

A)Stable nuclei have nucleon numbers less than 83.
B)Stable nuclei generally have odd atomic numbers.
C)Stable nuclei have atomic numbers greater than 83.
D)Stable nuclei generally have an odd number of neutrons.
E)Stable nuclei generally have more neutrons than protons.

Question 12

Assuming the radius of a hydrogen atom is given by the Bohr radius, r_Bohr = 5.29 × 10^-11 m, what is the ratio of the nuclear density of a hydrogen atom to its atomic density? Note: Assume for this calculation that the mass of the atom is equal to the mass of the proton.

A)1.2 × 10^-14
B)4.4 × 10⁴
C)8.6 × 10¹³
D)3.9 × 10¹⁷
E)2.3 × 10^-5

Question 13

How much energy is required to remove a neutron (m_n = 1.008 665 u) from that has an atomic mass of 15.000 108 u to make that has an atomic mass of 14.003 074 u? Note: The energy equivalent of the atomic mass unit is 931.5 MeV.

A)1.163 MeV
B)6.423 MeV
C)10.83 MeV
D)928.7 MeV
E)939.6 MeV

Question 14

The binding energy of an isotope of chlorine is 298 MeV.What is the mass defect of this chlorine nucleus in atomic mass units?

A)3.13 u
B)2.30 u
C)0.882 u
D)0.320 u
E)0.034 u

Question 15

Radiation or(and) particles emerge(s) from a radioactive sample.These products from the sample are allowed to pass through a narrow slit and may be considered a beam.The beam is passed between two plates that carry opposite electrical charge.The experimental region contains no magnetic fields.It is observed that the beam is deflected toward the negatively charged plate. Which one of the following statements is the best conclusion for this situation?

A)The beam is only $\alpha$ rays.
B)The beam is only $\beta$ ^- rays.
C)The beam is only $\gamma$ rays.
D)The beam could be either $\alpha$ rays or $\beta$ ⁺ rays.
E)The beam could be $\alpha$ rays, $\beta$ ⁺ rays, or $\gamma$ rays.

Question 16

Complete the following sentence: In a $\beta$ ⁺ decay process, the emitted particle is

A)an electron.
B)a neutron.
C)a positron.
D)a proton.
E)a photon.

Question 17

Which one of the following types of nuclear radiation is not affected by a magnetic field?

A)alpha particles
B)( $\beta$ ^- rays)
C)gamma rays
D)( $\beta$ ⁺ rays)
E)helium nuclei

Question 18

Which process is used in the operation of the smoke detector discussed in Cutnell and Johnson's text?

A)alpha decay
B)beta decay
C)gamma decay
D)X-ray absorption
E)proton absorption

Question 19

In a beta decay process, not all of the released energy is carried by the beta particle.Who proposed the existence of the neutrino in 1930 to account for the missing energy?

A)Niels Bohr
B)Erwin Schrödinger
C)Werner Heisenberg
D)Wolfgang Pauli
E)Enrico Fermi

Question 20

The nucleus of an atom has a radius of 5.61 × 10^-15 m.If the nucleus contains 45 protons, how many neutrons does the nucleus contain?

A)45
B)57
C)69
D)84
E)102

Question 21

The activity of carbon-14 in a sample of charcoal from an archaeological site is 0.04 Bq.Determine the age of the sample.The half-life of carbon-14 is 5730 years.

A)10 500 yr
B)12 500 yr
C)14 500 yr
D)16 500 yr
E)18 500 yr

Question 22

The activity of a carbon-14 sample is 0.1 Ci.If this sample is burned, what is the activity of the resulting CO₂?

A)zero curies
B)0.1 Ci
C)0.2 Ci
D)0.3 Ci
E)2.00 Ci

Question 23

Determine the activity of 6.0 × 10¹² atoms of Rn-220 that has a half-life of 56 s.

A)2.0 Ci
B)2.5 Ci
C)3.0 Ci
D)3.5 Ci
E)4.0 Ci

Question 24

Which one of the following statements is true concerning the radioisotope carbon-14 that is used in carbon dating?

A)Carbon-14 is produced by living cells.
B)Carbon-14 is produced during $\beta$ ^- decay.
C)Carbon-14 is produced by the decay of carbon-12.
D)Carbon-14 is produced by cells after they have died.
E)Carbon-14 is produced by cosmic rays striking the atmosphere.

Question 25

The ratio of the abundance of carbon-14 to carbon-12 in a sample of dead wood is one quarter the ratio for living wood.If the half-life of carbon-14 is 5730 years, which one of the following expressions determines how many years ago the wood died?

A)2 × 5730
B)4 × 5730
C)0.75 × 5730
D)0.50 × 5730
E)0.25 × 5730

Question 26

If the uranium nucleus is at rest before its decay, which one of the following statements is true concerning the final nuclei?

A)They have equal kinetic energies, but the thorium nucleus has much more momentum.
B)They have momenta of equal magnitudes, but the thorium nucleus has much more kinetic energy.
C)They have equal kinetic energies and momenta of equal magnitudes.
D)They have equal kinetic energies, but X has much more momentum.
E)They have momenta of equal magnitudes, but X has much more kinetic energy.

Question 27

Determine the amount of energy released in the following alpha decay process: The relevant atomic masses are = 234.043 299 u, =230.033 937 u, and = 4.002 603 u.

A)3.73 keV
B)927 keV
C)6.30 MeV
D)8.04 MeV
E)10.6 MeV

Question 28

Which process is involved in determining the age of a prehistoric object?

A)alpha decay
B)beta decay
C)gamma decay
D)X-ray absorption
E)proton absorption

Question 29

The same activity is measured for two different isotope samples.One sample contains 0.0450 kg of (atomic mass = 230.033 937 u, t_1/2 = 20.8 days).The second sample contains an unknown amount of (atomic mass = 231.036 264 u, t_1/2 = 4.3 days).What is the mass of the second sample?

A)0.0093 kg
B)0.23 kg
C)0.110 kg
D)0.037 kg
E)0.0450 kg

Question 30

Tritium is an isotope of hydrogen that has two neutrons in addition to its proton.Tritium undergoes $\beta$ ^- decay with a half-life of 12.3 years.What percentage of an initially pure sample of tritium will remain undecayed after 35 years?

A)2.9 %
B)6.0 %
C)7.0 %
D)14 %
E)19 %

Question 31

Determine the amount of energy released in this decay.Use the following atomic masses: Conversion factors: 1 u = 931.5 MeV; 1 eV = 1.602 × 10^-19 J

A)3.5 × 10^-8 J
B)6.0 × 10^-10 J
C)4.6 × 10^-12 J
D)7.3 × 10^-13 J
E)2.9 × 10^-12 J

Question 32

In a certain $\gamma$ decay process, an excited neon atom emits a $\gamma$ -ray that has an energy of 1.630 MeV.The neon atom in the ground state has a mass of 19.992 435 u.What is the mass of the excited neon atom?

A)17.498 658 u
B)18.746 422 u
C)19.994 185 u
D)19.999 685 u
E)20.003 185 u

Question 33

A sample contains 1000 nuclei of a radioactive isotope of barium.Exactly sixty seconds later, 970 nuclei in the sample have decayed.Determine the half-life of this isotope.

A)10 s
B)12 s
C)14 s
D)16 s
E)18 s