Nuclear Physics MCQs
The nucleus of an atom consists of:
Protons and electrons
Protons and neutrons
Neutrons and electrons
Electrons, protons, and neutrons
Isotopes are atoms of the same element with:
The same number of protons but different numbers of neutrons
The same number of neutrons but different numbers of protons
The same number of protons and neutrons
Different numbers of protons and neutrons
The mass of a neutron is approximately:
9.1 x 10⁻³¹ kg
1.67 x 10⁻²⁷ kg
1.6 x 10⁻¹⁹ kg
6.02 x 10²³ kg
One atomic mass unit (amu) is equivalent to:
931.5 MeV
1.66 x 10⁻²⁷ J
9.1 x 10⁻³¹ kg
1.6 x 10⁻¹⁹ C
The 'mass defect' in a nucleus is the:
Total mass of the protons and neutrons
Difference between nuclear mass and the sum of nucleon masses
Average mass of a nucleon
Mass of the electrons surrounding the nucleus
The force that holds the nucleons together in a nucleus is called the:
Gravitational force
Electromagnetic force
Strong nuclear force
Weak nuclear force
Which of the following has the highest penetrating power?
Alpha particles
Beta particles
Gamma rays
Protons
An alpha particle is essentially a nucleus of:
Hydrogen
Helium
Deuterium
Tritium
In beta decay, a neutron is converted into:
A proton, an electron, and an antineutrino
A proton and a positron
A proton and a gamma ray
An electron and a positron
The half-life of a radioactive element is the time in which:
Half of the atoms decay
All of the atoms decay
One-fourth of the atoms decay
The element becomes stable
A sample contains 5 x 10¹² radioactive atoms. If its decay constant is 4 x 10⁻⁸ s⁻¹, what is the initial activity of the sample in Bq?
1.25 x 10²⁰ Bq
2.0 x 10⁵ Bq
20 x 10²⁰ Bq
0.8 x 10⁻²⁰ Bq
What is the approximate radius of an Aluminum (²⁷Al) nucleus? (Use R₀ ≈ 1.2 fm)
The half-life of Technetium-99m is 6 hours. What percentage of a sample remains undecayed after one full day (24 hours)?
The SI unit of radioactivity is the:
Curie
Rutherford
Becquerel
Roentgen
A Geiger-Müller counter is used to detect:
The charge of an electron
The mass of a proton
Ionizing radiation
The presence of a magnetic field
The process of splitting a heavy nucleus into two lighter nuclei is called:
Nuclear fusion
Nuclear fission
Radioactive decay
Electron capture
In a nuclear reactor, the moderator is used to:
Absorb neutrons
Slow down fast neutrons
Accelerate neutrons
Start the chain reaction
Which of the following is commonly used as a moderator in a nuclear reactor?
Boron
Cadmium
Heavy water
Uranium
Nuclear fusion is the process in which:
A heavy nucleus is split
Two or more light nuclei combine to form a heavier nucleus
Electrons are emitted from a nucleus
A neutron is absorbed by a nucleus
The energy of the sun is primarily a result of:
Nuclear fission
Chemical reactions
Nuclear fusion
Gravitational collapse
The Wilson cloud chamber is used to:
Measure the energy of radiation
Detect the path of charged particles
Accelerate particles
Split atomic nuclei
A solid-state detector is essentially a:
Gas-filled chamber
Scintillating material
Reverse-biased p-n junction
Photographic plate
In the nuclear reaction U-235 + n -> Ba-141 + Kr-92 + 3n, the process is:
Alpha decay
Beta decay
Nuclear fission
Nuclear fusion
The binding energy per nucleon is maximum for:
Light nuclei
Heavy nuclei
Medium-sized nuclei (like iron)
Noble gases
A radioactive sample has a half-life of 20 minutes. What fraction of the sample will be left undecayed after 1 hour?
The mass defect of a certain nucleus is 0.04 amu. What is its binding energy? (Use 1 amu = 931.5 MeV)
37.26 MeV
93.15 MeV
23.28 MeV
0.04 MeV
High-energy electrons
High-energy photons
Helium nuclei
Positrons
The charge of an alpha particle is:
The half-life of carbon-14 is approximately:
5730 years
4.5 billion years
1600 years
12.3 years
Which of the following is not a fundamental force of nature?
Strong nuclear force
Weak nuclear force
Frictional force
Gravitational force
The phenomenon of natural radioactivity was discovered by:
Marie Curie
Pierre Curie
Henri Becquerel
Ernest Rutherford
In the equation E = mc², 'c' represents:
The charge of an electron
The speed of light in a vacuum
The Planck constant
The Avogadro constant
The control rods in a nuclear reactor are typically made of:
Graphite
Heavy water
Cadmium
Uranium
When a nucleus emits a gamma ray, its atomic number:
Increases by 1
Decreases by 1
Remains the same
Decreases by 2
After two half-lives, the fraction of the original radioactive sample that remains is:
The decay constant (λ) is related to the half-life (T₁/₂) by the equation:
λ = T₁/₂ / 0.693
λ = 0.693 / T₁/₂
λ = 0.693 * T₁/₂
λ = 1 / T₁/₂
The 'dead time' of a Geiger-Müller counter is the time:
Before it can detect any radiation
During which it cannot detect another particle after one has been detected
For which it can be used before being replaced
For the gas to ionize
In a fusion reaction, the mass of the products is:
Greater than the mass of the reactants
Less than the mass of the reactants
Equal to the mass of the reactants
Dependent on the temperature
The range of the strong nuclear force is approximately:
10⁻¹⁰ m
10⁻¹⁵ m
10⁻⁵ m
Infinite
An antineutrino is emitted during:
Alpha decay
Positive beta decay (positron emission)
Negative beta decay
Gamma decay
A chain reaction in a nuclear reactor is sustained by:
Protons
Neutrons
Electrons
Alpha particles
The principle of a solid-state detector is based on the creation of:
Electron-hole pairs
Ion pairs
Scintillations
A magnetic field
The study of the age of geological samples can be done using:
Carbon dating
Uranium dating
Both
None of the above
Which of the following particles has no charge and no mass (or very little mass)?
Proton
Neutron
Electron
Neutrino
The unit 'roentgen' is used to measure:
Radiation dose
Radioactivity
Radiation exposure
Half-life
Type of radiation detector
Stable isotope
Radioactive isotope used to trace a process
Particle accelerator
In the reaction ¹⁴N + ⁴He -> X + ¹H, the nucleus X is:
The binding energy per nucleon curve shows that:
Fusion of light nuclei releases energy
Fission of heavy nuclei releases energy
Both
None of these
Which of the following is the most stable nucleus?
Hydrogen-1
Uranium-238
Iron-56
Helium-4
Background radiation is due to:
Cosmic rays
Radioactive elements in the Earth's crust
Radioactive isotopes in the atmosphere (like carbon-14)
All of the above
Pair production is the conversion of:
A proton into a neutron and a positron
A neutron into a proton and an electron
A photon into an electron-positron pair
An electron and a positron into a photon
The critical mass is the minimum mass of a fissile material required to:
Start a nuclear reaction
Sustain a chain reaction
Undergo fusion
Act as a moderator
In radiotherapy, cancer cells are destroyed by:
Heating them
Using chemical reactions
Exposing to controlled radiation
Freezing them
The atomic number (Z) of a nucleus represents the number of:
Neutrons
Protons
Nucleons
Electrons in the neutral atom
Which statement is true for the strong nuclear force?
It is charge-dependent.
It has a very long range.
It is the weakest of the fundamental forces.
It is charge-independent and has a short range.
A nucleus of thorium ²³²Th decays to radium ²²⁸Ra. What type of decay is this?
Alpha decay
Beta decay
Gamma decay
Positron emission
The half-life of a radioactive substance is 10 days. What will be the amount left after 30 days if the initial amount is 8 grams?
4 grams
2 grams
1 gram
0 grams
The ratio of the mass numbers of two nuclei is 64:27. What is the ratio of their nuclear radii?
The activity of a radioactive sample is 800 Bq. If its half-life is 5 days, what will its activity be after 20 days?
The mean life (τ) of a radioactive nuclide is related to its decay constant (λ) by:
τ = λ
τ = 1/λ
τ = 0.693 / λ
τ = λ / 0.693
For a nuclear fusion reaction to occur, the temperature and pressure must be extremely high in order to:
Overcome the strong nuclear force.
Overcome the electrostatic repulsion between nuclei.
Break nuclei apart before they can fuse.
Provide activation energy for a chemical reaction.
Which of the following is NOT a component of a nuclear power reactor?
Moderator
Particle accelerator
Coolant
Radiation shield
In a Geiger-Müller counter, the gas used is typically:
A noble gas like argon mixed with a quenching agent.
Pure oxygen.
Hydrogen sulfide.
Carbon dioxide.
The 'quenching' process in a G-M tube is necessary to:
Initiate the detection of a particle.
Amplify the electrical signal.
Prevent a continuous discharge.
Cool the detector.
Annihilation of matter occurs when:
A high-energy photon creates a particle-antiparticle pair.
A nucleus undergoes fission.
An electron and a positron collide.
Two light nuclei fuse.
A radioactive tracer used in medical imaging should ideally have:
A very long half-life and emit alpha particles.
A very long half-life and emit gamma rays.
A short half-life and emit alpha particles.
A short half-life and emit gamma rays.
Which of the following correctly lists radiation types in order of increasing ionizing power?
Gamma < Beta < Alpha
Alpha < Beta < Gamma
Beta < Gamma < Alpha
Gamma < Alpha < Beta
The concept of a nucleus was first proposed by Rutherford based on his:
Discovery of radioactivity.
Gold foil experiment.
Work on nuclear fission.
Study of cathode rays.
The half-life of a radioactive nucleus is 200 seconds. What is its approximate mean life (average lifetime)?
What fraction of a radioactive sample remains after 9 years if its half-life is 3 years?
The activity of a sample is 1.2 x 10⁶ Bq, and its decay constant is 3.0 x 10⁻⁹ s⁻¹. Approximately how many radioactive atoms are present in the sample?
3.6 x 10⁻³
2.5 x 10⁻¹⁵
4.0 x 10¹⁴
4.0 x 10¹⁶
If the decay constant of a radioactive sample is large, its half-life is:
Large
Small
Unaffected
Infinite
A 'thermal' neutron is a neutron that has:
Been heated to a very high temperature.
Been slowed down to have kinetic energy comparable to the surrounding atoms.
A very high kinetic energy.
Been released during a thermonuclear reaction.
The energy released in a nuclear reaction corresponds to the:
Sum of the kinetic energies of the reactants.
Total binding energy of the heavy nucleus.
Decrease in mass during the reaction.
Increase in mass during the reaction.
The penetration of radiation through matter is a process that is:
Certain
Chemical
Statistical
Reversible
Which particle is its own antiparticle?
Electron
Proton
Neutron
Photon
The fuel in most common types of nuclear reactors is:
Plutonium-239
Uranium-238
Uranium-235
Thorium-232
What happens to the neutron-to-proton ratio of a nucleus after it undergoes negative beta decay?
It increases.
It decreases.
It remains the same.
It becomes zero.
A breeder reactor is designed to:
Consume more fissile fuel than it produces.
Generate electrical power without any nuclear fuel.
Produce more fissile fuel than it consumes.
Exclusively use nuclear fusion for energy.
Calculate the energy released in the fusion reaction: ²₁H + ²₁H → ³₂He + ¹₀n. Given masses: ²H=2.0141 amu, ³He=3.0160 amu, n=1.0087 amu.
1.02 MeV
3.26 MeV
4.03 MeV
5.61 MeV
A radioactive source with a half-life of 28 years has an activity of 1000 Bq. How many years will it take for its activity to reduce to 125 Bq?
28 years
56 years
84 years
112 years
A stationary nucleus of ²³⁸U decays, releasing 4.27 MeV of energy. What is the approximate kinetic energy of the resulting alpha particle?
4.27 MeV
4.20 MeV
2.14 MeV
0.07 MeV
The visible tracks in a Wilson cloud chamber are made of:
Smoke
The particles themselves
Condensed vapor droplets
Ionized gas
The atomic mass unit (amu) is defined as:
The mass of one proton.
1/16th the mass of an oxygen-16 atom.
1/12th the mass of a carbon-12 atom.
The mass of one hydrogen-1 atom.
In the notation ᴬzX, the neutron number N is given by:
N = A
N = Z
N = A - Z
N = A + Z
Radioactive decay is a spontaneous process, which means:
It can be controlled by changing temperature and pressure.
It happens at a constant rate for all elements.
It occurs without any external trigger or influence.
It only happens for man-made isotopes.
In a nuclear reaction, the total mass of reactants is 4.0028 amu and the total mass of products is 4.0010 amu. How much energy is released in the reaction?
1.677 MeV
4.002 MeV
0.0018 MeV
931.5 MeV
The half-life of Radium-226 is 1600 years. What is its decay constant (λ) in yr⁻¹? (Use ln(2) ≈ 0.693)
4.33 x 10⁻⁴ yr⁻¹
2315 yr⁻¹
1108.8 yr⁻¹
1600 yr⁻¹
The binding energy of a Lithium nucleus (⁷₃Li) is 39.2 MeV. What is its approximate binding energy per nucleon?
13.0 MeV/nucleon
7.0 MeV/nucleon
5.6 MeV/nucleon
39.2 MeV/nucleon
Which of the following is a 'lepton'?
Proton
Neutron
Electron
Pion
The activity of a radioactive sample is measured in Becquerels (Bq). This is a measure of:
The total number of atoms in the sample.
The energy of the radiation emitted.
The rate at which decays occur.
The penetrating power of the radiation.
In the core of the sun, the proton-proton cycle results in the formation of:
Which detector would be most suitable for accurately measuring the energy of incoming radiation?
Geiger-Müller counter
Solid-state detector
Wilson cloud chamber
Bubble chamber
A nucleus of ²¹⁰Po decays into ²⁰⁶Pb. How many alpha and beta decays have occurred?
1 alpha, 2 beta
1 alpha, 0 beta
2 alpha, 1 beta
1 alpha, 4 beta
The biological effect of radiation is measured in which unit?
Becquerel
Gray
Sievert
Curie
A stable nucleus generally has:
More protons than neutrons.
An equal number of protons and neutrons (for all masses).
A neutron-to-proton ratio that increases with Z for heavy nuclei.
More electrons than protons.
The force carrier (exchange particle) for the electromagnetic force is the:
Gluon
W boson
Photon
Graviton
Nuclear isomers are nuclei that have the same A and Z but differ in their:
Energy states
Number of electrons
Shape
Spin direction
The minimum energy required for a photon to cause pair production is:
0.511 MeV
931.5 MeV
1.022 MeV
8.0 MeV
Which of the following processes is responsible for element-building (nucleosynthesis) in stars heavier than the sun?
Proton-proton cycle
Alpha decay
CNO cycle
Photodisintegration
The 'coolant' in a nuclear reactor is a substance used to:
Slow down neutrons.
Absorb neutrons.
Transfer heat from the core.
Shield the surroundings from radiation.
If a nucleus captures an electron from an inner atomic shell, the process is called:
Internal conversion
Compton effect
Electron capture
Pair annihilation
Which of the following statements about neutrinos is FALSE?
They are chargeless.
They have very little mass.
They interact very weakly with matter.
They travel faster than the speed of light.
The binding energy per nucleon curve's shape is due to the interplay between:
The strong nuclear force and the weak nuclear force.
The strong nuclear force and the electromagnetic force.
The electromagnetic force and gravity.
The weak nuclear force and gravity.
In a bubble chamber, the paths of particles are seen as:
Trails of dark spots on a film.
Trails of tiny bubbles in a liquid.
Flashes of light.
A series of electrical pulses.
The half-life of Radon-222 is 3.8 days. A sample will be reduced to 1/16th of its original amount in:
3.8 days
7.6 days
11.4 days
15.2 days
Which particle completes this nuclear reaction: ⁹Be + ⁴He -> ¹²C + ?
Proton (¹H)
Neutron (¹n)
Electron (⁰e)
Gamma ray (γ)
Radioisotopes used in smoke detectors, such as Americium-241, typically emit:
Alpha particles
Beta particles
Gamma rays
Neutrons
The term 'nucleon' refers to:
Only a proton.
Only a neutron.
Either a proton or a neutron.
The nucleus of a helium atom.
The half-life of a radioisotope is 10 hours. How long will it take for 87.5% of the sample to decay?
10 hours
20 hours
30 hours
40 hours
Given: mass of proton = 1.0073 amu, mass of neutron = 1.0087 amu. Calculate the mass defect of a Helium nucleus (⁴₂He) which has a mass of 4.0026 amu.
0.0304 amu
4.0320 amu
0.0026 amu
2.0160 amu
How much energy in Joules is equivalent to a mass of 2.0 nanograms (2.0 x 10⁻¹² kg)? (Use c = 3 x 10⁸ m/s)
1.8 x 10⁵ J
6.0 x 10⁻⁴ J
1.8 x 10¹³ J
9.0 x 10⁴ J
Why is the energy spectrum of beta particles continuous?
The parent nucleus is heavier.
The decay energy is shared between the beta particle and neutrino.
The daughter nucleus is left in an excited state.
Beta particles have less mass than alpha particles.
The purpose of a radiation shield around a nuclear reactor is primarily to absorb:
Heat and light
Sound and vibrations
Neutrons and gamma rays
Carbon dioxide emissions
If the radius of a nucleus with A=3 is R, what will be the approximate radius of a nucleus with A=81?
If 1.0 kg of a substance is completely converted into energy, how much energy is produced? (c = 3 x 10⁸ m/s)
3 x 10⁸ J
9 x 10⁸ J
3 x 10¹⁶ J
9 x 10¹⁶ J
Other Physics Topics MCQs
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