by Question 1: The nuclear radius is directly proportional to:
Options: A) Atomic number (Z) B) Mass number (A) C) Square of atomic number D) Cube of mass number
✅ Correct Answer: B) Mass number (A)
Explanation:
The nuclear radius is given by the formula:This shows that the nuclear radius depends on the mass number, not on the atomic number.
Question 2: Which force is responsible for holding the nucleons together in a nucleus?
Options: A) Gravitational force B) Electromagnetic force C) Strong nuclear force D) Weak nuclear force
✅ Correct Answer: C) Strong nuclear force
Explanation: The strong nuclear force is the strongest fundamental force and acts between nucleons (protons and neutrons) to hold the nucleus together, overcoming the electromagnetic repulsion between protons.
Question 3: The charge of the nucleus is due to:
Options: A) Neutrons B) Protons C) Electrons D) Both a and b
✅ Correct Answer: B) Protons
Explanation: Protons carry a positive charge (+e), while neutrons are electrically neutral. Electrons are outside the nucleus. Therefore, nuclear charge comes entirely from protons.
Question 4: The unit of nuclear radius is typically:
Options: A) Metre B) Angstrom C) Nanometer D) Femtometre
✅ Correct Answer: D) Femtometre
Explanation: Nuclear dimensions are extremely small, typically measured in femtometres (fm), where 1 fm = 10⁻¹⁵ m. Nuclear radii are typically a few femtometres.
Question 5: If a nucleus has 20 protons and 22 neutrons, its mass number and atomic number, respectively,y are:
Options: A) 42 and 20 B) 20 and 22 C) 22 and 20 D) 42 and 22
✅ Correct Answer: A) 42 and 20
Explanation: Mass number (A) = protons + neutrons = 20 + 22 = 42. Atomic number (Z) = number of protons = 20.
Question 6: The stability of a nucleus depends mainly on the:
Options: A) Number of electrons B) Mass number C) Neutron-to-proton ratio D) Binding energy of electrons
✅ Correct Answer: C) Neutron-to-proton ratio
Explanation: Nuclear stability depends critically on the neutron-to-proton (n/p) ratio. For light nuclei, n/p ≈ 1, while for heavier nuclei, more neutrons are needed for stability.
Question 7: Which fundamental force is responsible for keeping electrons bound to the nucleus?
Options: A) Weak nuclear force B) Gravitational force C) Electromagnetic force D) Strong nuclear force
✅ Correct Answer: C) Electromagnetic force
Explanation: The electromagnetic (Coulomb) force between the positively charged nucleus and negatively charged electrons keeps electrons bound in atoms.
Question 8: The force responsible for the radioactive beta decay is:
Options: A) Weak nuclear force B) Strong nuclear force C) Gravitational force D) Electromagnetic force
✅ Correct Answer: A) Weak nuclear force
Explanation: Beta decay involves the transformation of a neutron into a proton (or vice versa), which is mediated by the weak nuclear force.
Question 9: Which of the following particles mediates the electromagnetic forces?
Options: A) Photon B) Gluon C) W and Z bosons D) Graviton
✅ Correct Answer: A) Photon
Explanation: Photons are the exchange particles (gauge bosons) that mediate electromagnetic interactions between charged particles.
Question 10: The particles that mediate the strong nuclear force are called:
Options: A) Photons B) Gravitons C) Gluons D) W bosons
✅ Correct Answer: C) Gluons
Explanation: Gluons are the exchange particles that mediate the strong nuclear force between quarks and hold nucleons together.
Question 11: Which one of the following pairs of particles causes annihilation?
Options: A) Proton-proton B) Proton-neutron C) Neutron-photon D) Electron-positron
✅ Correct Answer: D) Electron-positron
Explanation: Annihilation occurs when a particle meets its antiparticle. Electrons and positrons are particle-antiparticle pairs that annihilate to produce gamma rays.
Question 12: The antiparticle of an electron is:
Options: A) Proton B) Positron C) Neutrino D) Anti-proton
✅ Correct Answer: B) Positron
Explanation: The positron (e⁺) is the antiparticle of the electron (e⁻). It has the same mass as an electron but an opposite (positive) charge.
Question 13: When a particle and its antiparticle meet, what happens?
Options: A) They bounce off .B) They fuse. C) They annihilate, releasing energy.y D) They become dark matter
✅ Correct Answer: C) They annihilate, releasing energy
Explanation: When a particle and its antiparticle meet, they annihilate, converting their mass into energy (usually gamma-ray photons) according to E = mc².
Question 14: Which scientist is credited with the prediction of the eexistenceof antimatter?
Options: A) Albert Einstein B) Paul Dirac C) Niels Bohr D) Richard Feynman
✅ Correct Answer: B) Paul Dirac
Explanation: Paul Dirac predicted the existence of antimatter in 1928 using his relativistic quantum-mechanical equation (the Dirac equation).
Question 15: In which type of matter (antimatter) are particles created from energy?
Options: A) Nuclear fission B) Combustion C) Pair production D) Fusion
✅ Correct Answer: C) Pair production
Explanation: Pair production is the process by which a high-energy photon creates a particle-antiparticle pair (typically electron-positron) from pure energy.
Question 16: What would happen if antimatter came into contact with Earth’s atmosphere?
Options: A) Nothing, B) It would cool down, C) It would instantly annihilate with matter, releasing large amounts of energy, D) It would sink into the Earth’s core
✅ Correct Answer: C) It would instantly annihilate with matter, releasing large amounts of energy
Explanation: Antimatter would immediately annihilate with regular matter in the atmosphere, producing gamma rays and releasing enormous energy.
Question 17: Which of the following medical technological concepts of antimatter?
Options: A) MRI B) X-ray C) CT scan D) PET scan
✅ Correct Answer: D) PET scan
Explanation: PET (Positron Emission Tomographyapusesuses positrons (antimatter) emitted by radioactive tracers. When positrons annihilate with electrons, gamma rays are emitted, which are detected to create images.
Question 18: Pair production can only occur if the photon has energy:
Options: A) Less than 0.5 MeV B) Exactly 0.51 MeV C) Greater than 1.02 MeV D) Greater than 0.1 MeV
✅ Correct Answer: C) Greater than 1.02 MeV
Explanation: The minimum energy needed is 2m_ec² = 2 × 0.511 MeV = 1.02 MeV to create an electron-positron pair.
Question 19: Which of the following is conserved during pair production?
Options: A) Energy only B) Momentum only C) Mass only D) Energy and momentum
✅ Correct Answer: D) Energy and momentum
Explanation: Both energy and momentum must be conserved in pair production. This is why pair production cannot occur in a vacuum alone and requires a nearby nucleus.
antimatter: In matter-antimatter annihilation, the energy released appears in the form of:
Options: A) Alpha particles B) Neutrinos C) Photons (gamma rays) D) Electrons
✅ Correct Answer: C) Photons (gamma rays)
Explanation: Electron-positron annihilation typically produces two gamma-ray photons moving in opposite directions to conserve momentum.
Question 21: Pair production is a process in which a photon is converted into:
Options: A) Two protons, B) A neutron, a positron, C) Two neutrons, D) An electron and a positron
✅ Correct Answer: D) An electron and a positron
Explanation: In pair production, a high-energy photon converts into an electron-positron pair.
Question 22: In annihilation, an electron and a positron combine to produce:
Options: A) One gamma photon B) Two gamma photons C) Three gamma photons D) A proton and a neutron
✅ Correct Answer: B) Two gamma photons
Explanation: Electron-positron annihilation produces two gamma photons moving in opposite directions to conserve both energy and momentum.
Question 23: Which conservation law is obeyed during pair production and annihilation?
Options: A) Only energy B) Only charge C) Energy, momentum and charge D) Only mass
✅ Correct Answer: C) Energy, momentum and charge
Explanation: All three quantities are conserved: energy (E = mc²), momentum (requires nucleus or produces two photons), and charge (net charge = 0 before and after).
Question 24: When a neutron changes into a proton, we will observe:
Options: A) β⁻-decay B) β⁺-decay C) γ-decay D) α-decay
✅ Correct Answer: A) β⁻-decay
Explanation: In β⁻ decay, a neutron transforms into a proton, emitting an electron (β⁻) and an antineutrino: n → p + e⁻ + ν̄.
Question 25: Which one of the following radiation/particles has the highest ionisation power?
Options: A) α B) β⁺ C) β⁻ D) γ
✅ Correct Answer: A) α
Explanation: Alpha particles are heavy, doubly-charged particles that interact strongly with matter, producing the most ionisation per unit path length.
Question 26: Which one of the following has the highest radiation/particles penetrating power?
Options: A) α B) β⁺ C) β⁻ D) γ
✅ Correct Answer: D) γ
Explanation: Gamma rays are uncharged electromagnetic radiation with the highest penetrating power. They can pass through several centimetres of lead.
Question 27: A change occurs in the atomic number of a nucleus, but its mass number remains the same by decay of:
Options: A) α B) β⁺ C) γ D) γ and α
✅ Correct Answer: B) β⁺
Explanation: In beta decay (β⁺ or β⁻), the mass number remains constant while the atomic number changes by ±1.
Question 28: In a nucleus, a neutron changes into a proton, the atomic number changes by one, and the mass number will:
Options: A) Decrease B) Increase C) Remain the same D) None of these
✅ Correct Answer: C) Remain the same
Explanation: Since both neutrons and protons contribute to the mass number, converting one to the other doesn’t change the total: A = Z + N remains constant.
Question 29: Which of the following particles has the highest penetrating power?
Options: A) Gamma rays B) Alpha particles C) Beta particles D) Neutrons
✅ Correct Answer: A) Gamma rays
Explanation: Gamma rays, being uncharged electromagnetic radiation, have the highest penetrating power among common radioactive emissions.
Question 30: In alpha-decay, the mass number of the nucleus:
Options: A) Increases by 4 B) Decreases by 4 C) Increases by 2 D) Remains unchanged
✅ Correct Answer: B) Decreases by 4
Explanation: An alpha particle consists of 2 protons and 2 neutrons, so the mass number decreases by 4 when it’s emitted.
Question 31: Beta-decay results in the emission of:
Options: A) A helium nucleus B) An electron or positron C) A photon D) A neutron
✅ Correct Answer: B) An electron or positron
Explanation: Beta-minus decay emits an electron, while beta-plus decay emits a positron. Both are forms of beta decay.
Question 32: Which of the following is not affected by electric and magnetic fields?
Options: A) Alpha particles B) Beta particles C) Gamma rays D) Electrons
✅ Correct Answer: C) Gamma rays
Explanation: Gamma rays are uncharged electromagnetic radiation and are not deflected by electric or magnetic fields, unlike charged particles.
Question 33: Which radioactive emission increases the atomic number by 1 but leaves the mass number unchanged?
Options: A) Alpha emission B) Gamma emission C) Beta-plus emission D) Beta-minus emission
✅ Correct Answer: D) Beta-minus emission
Explanation: In β⁻ decay, a neutron converts to a proton, increasing Z by 1 while A remains constant (n → p + e⁻ + ν̄).
Question 34: The SI unit of radioactivity is:
Options: A) Curie B) Becquerel C) Rutherford D) Sievert
✅ Correct Answer: B) Becquerel
Explanation: The Becquerel (Bq) is the SI unit of radioactivity, defined as one decay per second. The Curie is an older unit.
Question 35: The particle emitted in alpha decay is:
Options: A) Helium nucleus B) Electron C) Neutron D) Positron
✅ Correct Answer: A) Helium nucleus
Explanation: An alpha particle is a helium-4 nucleus, consisting of 2 protons and 2 neutrons (₂⁴He).
Question 36: Which radiation is deflected by electric and magnetic fields?
Options: A) Alpha and beta, B) Gonlya only,y C) onlypha only,ly D) Gamma and beta
✅ Correct Answer: A) Alpha and beta
Explanation: Both alpha and beta particles are charged and are therefore deflected by electric and magnetic fields. Gamma rays are not deflected.
Question 37: During Beta-minus decay, the atomic number of the nucleus:
Options: A) Decreases by 1 B) Remains unchanged C) Increases by 2 D) Increases by 1
✅ Correct Answer: D) Increases by 1
Explanation: In β⁻ decay, a neutron converts to a proton, increasing the atomic number by 1.
Question 38: In Beta-plus decay, which particle is emitted?
Options: A) Electron B) Neutron C) Positron D) Proton
✅ Correct Answer: C) Positron
Explanation: In β⁺ decay, a proton converts to a neutron, emitting a positron and a neutrino: p → n + e⁺ + ν.
Question 39: adecayaycay, the atomic number of the nucleus:
Options: A) Increases by 2 B) Decreases by 2 C) Increases by 4 D) Remains unchanged
✅ Correct Answer: B) Decreases by 2
Explanation: An alpha particle contains 2 protons, so when emitted, the atomic number decreases by 2.
Question 40: Which type of decay is the most penetrating?
Options: A) Alpha B) Beta C) Gamma D) None of these
✅ Correct Answer: C) Gamma
Explanation: Gamma radiation has the highest penetrating power, requiring thick lead or concrete shielding.
Question 41: Which of the following radiation types can be stopped by a sheet of paper?
Options: A) Alpha B) Beta C) Gamma D) All of these
✅ Correct Answer: A) Alpha
Explanation: Alpha particles have low penetrating power and can be stopped by a sheet of paper or even skin.
Question 42: Gamma rays are a form of:
Options: A) Sound waves B) Charged particles C) Electromagnetic radiation D) Nuclear matter
✅ Correct Answer: C) Electromagnetic radiation
Explanation: Gamma rays are high-energy electromagnetic radiation, similar to X-rays but with higher energy.
Question 43: Which one of the following is the fundamental particle?
Options: A) Proton B) Neutron C) Electron D) Meson
✅ Correct Answer: C) Electron
Explanation: Electrons are truly fundamental (point particles). Protons and neutrons are composite particles made of quarks.
Question 44: Which one of the following forces has a negligible effect between the elementary particles?
Options: A) Strong nuclear force B) Weak force C) Gravitational force D) Electromagnetic force
✅ Correct Answer: C) Gravitational force
Explanation: Gravitational force is extremely weak at the subatomic scale and has a negligible effect between elementary particles.
Question 45: A baryon is formed by the combination of:
Options: A) 2 quarks B) 3 quarks C) 4 quarks D) A quark and an antiquark
✅ Correct Answer: B) 3 quarks
Explanation: Baryons (like protons and neutrons) are composite particles made of three quarks.
Question 46: A proton is composed of up and down quarks. The order of quarks is:
Options: A) udd B) udu C) uud D) dud
✅ Correct Answer: C) uud
Explanation: A proton consists of two up quarks and one down quark (uud).
Question 47: The number of quarks that compose a neutron is:
Options: A) 2 B) 3 C) 4 D) 5
✅ Correct Answer: B) 3
Explanation: A neutron, like all baryons, is composed of 3 quarks (specifically: udd).
Question 48: Which of the following is a fundamental particle?
Options: A) Proton B) Neutron C) Electron D) Alpha particle
✅ Correct Answer: C) Electron
Explanation: Electrons are fundamental leptons. Protons and neutrons are made of quarks, and alpha particles are composite.
Question 49: Which of the following is not a lepton?
Options: A) Electron B) Neutrinos C) Muon D) Proton
✅ Correct Answer: D) Proton
Explanation: A proton is a baryon (made of quarks). Electrons, neutrinos, and muons are all leptons.
Question 50: Quarks are the building blocks of:
Options: A) Electron B) Protons and neutrons C) Photons D) Neutrinos
✅ Correct Answer: B) Protons and neutrons
Explanation: Quarks combine to form hadrons, including baryons (protons and neutrons) and mesons.
Question 51: How many types (flavours) of quarks are known?
Options: A) 3 B) 4 C) 5 D) 6
✅ Correct Answer: D) 6
Explanation: There are six quark flavours: up, down, charm, strange, top, and bottom.
Question 52: Which of the following particles is massless?
Options: A) Neutron B) Photon C) Electron D) Neutrino
✅ Correct Answer: B) Photon
Explanation: Photons have zero rest mass. Note: Neutrinos have a tiny mass, not zero.
Question 53: The particle responsible for giving mass to other particles is the:
Options: A) Electron B) Neutron C) Higgs boson D) Proton
✅ Correct Answer: C) Higgs boson
Explanation: The Higgs boson is associated with the Higgs field, which gives mass to fundamental particles through the Higgs mechanism.
Question 54: Quarks combine to form:
Options: A) Proton B) Nucleons C) Photons D) Mesons and baryons
✅ Correct Answer: D) Mesons and baryons
Explanation: Quarks combine to form hadrons, which include mesons (quark-antiquark) and baryons (three quarks).
Question 55: Which of the following particles is a lepton?
Options: A) Proton B) Neutron C) Neutrino D) Gluon
✅ Correct Answer: C) Neutrino
Explanation: Neutrinos are leptons. Protons and neutrons are baryons, and gluons are gauge bosons.
Question 56: Whatthe rest mass of a photon?
Options: A) Equal to electron mass B) Very large C) Zero D) Equal to proton mass
✅ Correct Answer: C) Zero
Explanation: Photons are massless particles that always travel at the speed of light.
Question 57: Which two quarks make up a neutron?
Options: A) Up and down B) Down and strange C) Top and bottom D) Up and charm
✅ Correct Answer: A) Up and down
Explanation: A neutron consists of one up quark and two down quarks (udd).
Question 58: Quarks are held together by which fundamental force?
Options: A) Gravitational force B) Weak nuclear force C) Electromagnetic force D) Strong nuclear force
✅ Correct Answer: D) Strong nuclear force
Explanation: The strong nuclear force (mediated by gluons) binds quarks together to form hadrons.
Question 59: Which particle is hypothetical and has not yet been experimentally confirmed?
Options: A) Gluon B) Higgs boson C) Graviton D) Electron
✅ Correct Answer: C) Graviton
Explanation: The graviton is the hypothetical quantum of gravity that has not been experimentally detected. (Note: The Higgs boson was discovered in 2012.)
Question 60: Which quark is heaviest?
Options: A) Strange B) Bottom C) Top D) Charm
✅ Correct Answer: C) Top
Explanation: The top quark is the heaviest of all quarks, with a mass of about 173 GeV/c².
Question 61: Which combination of quarks makes up a proton?
Options: A) uud B) udd C) ddu D) uuu
✅ Correct Answer: A) uud
Explanation: A proton consists of two up quarks and one down quark (uud).
Question 62: Which field is associated with the Higgs boson?
Options: A) Magnetic field B) Gravitational field C) Higgs field D) Quantum field
✅ Correct Answer: C) Higgs field
Explanation: The Higgs boson is the quantum excitation of the Higgs field, which permeates all of space.
Question 63: A meson is made up of:
Options: A) Two quarks B) Three quarks C) One quark and one antiquark D) One proton and one neutron
✅ Correct Answer: C) One quark and one antiquark
Explanation: Mesons are hadrons composed of a quark-antiquark pair (e.g., pions, kaons).
Question 64: What is the quark composition of a neutron?
Options: A) uud B) uuu C) ddd D) udd
✅ Correct Answer: D) udd
Explanation: A neutron consists of one up quark and two down quarks (udd).
Question 65: Which of the following is not a flavour of quark?
Options: A) Top B) Bottom C) Muon D) Strange
✅ Correct Answer: C) Muon
Explanation: Muon is a lepton, not a quark. The six quark flavours are: up, down, charm, strange, top, and bottom.
Question 66: The Higgs boson is often referred to as:
Options: A) Golden particle B) Dark matter particle C) Supersymmetry particle D) Quantum field
✅ Correct Answer: A) Golden particle
Explanation: The Higgs boson is sometimes called the “God particle” (not in options), but among these choices, “Golden particle” is closest, though not standard terminology.
Question 67: What does the Higgs boson explain in the standard model of particle physics?
Options: A) Nature of gravity B) Speed of light C) Origin of mass D) Colour of quarks
✅ Correct Answer: C) Origin of mass
Explanation: The Higgs mechanism explains how fundamental particles acquire mass through interaction with the Higgs field.
Question 68: The field associated with the Higgs boson is called:
Options: A) Electromagnetic field B) Higgs field C) Gravitational field D) Quantum chromodynamics field
✅ Correct Answer: B) Higgs field
Explanation: The Higgs field is a quantum field that exists throughout space, and the Higgs boson is its quantum excitation.
Question 69: The Higgs boson is a type of:
Options: A) Lepton B) Quark C) Boson D) Fermion
✅ Correct Answer: C) Boson
Explanation: The Higgs boson is a scalar (spin-0 particle), distinct from fermions (spin-1/2) like quarks and leptons.
Question 70: Which fundamental force is directly associated with the Higgs mechanism?
Options: A) Strong nuclear force B) Weak nuclear force C) Electromagnetic force D) Gravitational force
✅ Correct Answer: B) Weak nuclear force
Explanation: The Higgs mechanism is intimately connected with electroweak symmetry breaking, giving mass to the W and Z bosons of the weak force.
Question 71: The Higgs boson field is present:
Options: A) Only in particle accelerators B) Only near black holes C) Everywhere in the universe D) Only in dark matter regions
✅ Correct Answer: C) Everywhere in the universe
Explanation: The Higgs field permeates all of space throughout the universe, and particles acquire mass by interacting with this field.
Question 72: The particle which does not interact with the Higgs field is:
Options: A) Photon B) Electron C) W boson D) Z boson
✅ Correct Answer: A) Photon
Explanation: Massless particles like photons and gluons do not interact with the Higgs field, which is why they have no mass.
