Q.1 Which of the following particles is found in the nucleus of an atom?
Electron
Proton
Neutrino
Photon
Explanation - The nucleus of an atom contains protons and neutrons. Electrons orbit around the nucleus.
Correct answer is: Proton
Q.2 What is the approximate half-life of Carbon-14?
5730 years
25 years
4.5 billion years
10 minutes
Explanation - Carbon-14 is a radioactive isotope used in radiocarbon dating with a half-life of about 5730 years.
Correct answer is: 5730 years
Q.3 Which nuclear reaction is used in a nuclear fission reactor?
Fusion of hydrogen nuclei
Fission of heavy nuclei
Electron capture
Alpha decay
Explanation - Nuclear fission involves splitting a heavy nucleus like Uranium-235 into smaller nuclei, releasing energy.
Correct answer is: Fission of heavy nuclei
Q.4 The energy released in nuclear reactions comes primarily from:
Electromagnetic forces
Gravitational forces
Strong nuclear forces
Weak nuclear forces
Explanation - The strong nuclear force binds protons and neutrons in the nucleus; breaking or forming these bonds releases nuclear energy.
Correct answer is: Strong nuclear forces
Q.5 Which of the following isotopes is commonly used in medical imaging?
Uranium-238
Technetium-99m
Plutonium-239
Carbon-12
Explanation - Technetium-99m is widely used in diagnostic imaging due to its suitable half-life and gamma radiation emission.
Correct answer is: Technetium-99m
Q.6 Which particle has no electric charge and is found in the nucleus?
Proton
Electron
Neutron
Alpha particle
Explanation - Neutrons are neutral particles in the nucleus, contributing to the mass of the atom.
Correct answer is: Neutron
Q.7 Which law governs the decay rate of radioactive substances?
Newton's Law
Law of Conservation of Mass
Exponential decay law
Ohm's Law
Explanation - Radioactive decay follows an exponential law, with the number of undecayed nuclei decreasing exponentially over time.
Correct answer is: Exponential decay law
Q.8 In nuclear fusion, energy is released because:
Mass increases
Mass is converted into energy
Temperature decreases
Momentum decreases
Explanation - Fusion releases energy according to Einstein’s equation E=mc^2, where a small mass defect is converted to energy.
Correct answer is: Mass is converted into energy
Q.9 Which of the following is a product of Uranium-235 fission?
Helium-4
Krypton-92
Oxygen-16
Carbon-14
Explanation - Uranium-235 fission produces smaller nuclei like Krypton-92 and Barium-141 along with neutrons and energy.
Correct answer is: Krypton-92
Q.10 The binding energy of a nucleus is:
Energy required to break the nucleus into protons and neutrons
Kinetic energy of electrons
Energy released in chemical reactions
Potential energy of atoms
Explanation - Binding energy measures the stability of a nucleus; higher binding energy means a more stable nucleus.
Correct answer is: Energy required to break the nucleus into protons and neutrons
Q.11 Which decay involves emission of two protons and two neutrons?
Alpha decay
Beta decay
Gamma decay
Electron capture
Explanation - Alpha decay releases an alpha particle, which consists of two protons and two neutrons (essentially a helium nucleus).
Correct answer is: Alpha decay
Q.12 Which type of radiation has the highest penetrating power?
Alpha rays
Beta rays
Gamma rays
Positrons
Explanation - Gamma rays are electromagnetic waves with no mass or charge and have the highest penetration ability among common nuclear radiations.
Correct answer is: Gamma rays
Q.13 The unit of radioactive decay is:
Becquerel
Coulomb
Tesla
Newton
Explanation - 1 Becquerel (Bq) corresponds to one decay per second.
Correct answer is: Becquerel
Q.14 Which isotope is used in PET scans?
Carbon-14
Fluorine-18
Uranium-235
Technetium-99m
Explanation - Fluorine-18 is a positron-emitting isotope used in positron emission tomography (PET) scans for imaging.
Correct answer is: Fluorine-18
Q.15 Which nuclear force acts over a very short range inside the nucleus?
Gravitational force
Electromagnetic force
Strong nuclear force
Weak nuclear force
Explanation - Strong nuclear force is the force that holds protons and neutrons together inside the nucleus, acting over femtometer distances.
Correct answer is: Strong nuclear force
Q.16 Which particle is emitted in beta minus decay?
Proton
Electron
Neutron
Alpha particle
Explanation - In beta minus decay, a neutron converts into a proton and emits an electron (beta particle) and an antineutrino.
Correct answer is: Electron
Q.17 Which of these isotopes is stable?
Uranium-238
Carbon-12
Polonium-210
Technetium-99m
Explanation - Carbon-12 is a stable isotope of carbon and does not undergo radioactive decay.
Correct answer is: Carbon-12
Q.18 Neutrinos are emitted during which type of nuclear reaction?
Alpha decay
Beta decay
Gamma decay
Fission only
Explanation - Neutrinos (or antineutrinos) are emitted to conserve lepton number and energy during beta decay.
Correct answer is: Beta decay
Q.19 Which of the following is not a type of radioactive decay?
Alpha decay
Beta decay
Gamma decay
Delta decay
Explanation - Delta decay does not exist; common radioactive decays are alpha, beta, and gamma decay.
Correct answer is: Delta decay
Q.20 In a nuclear reactor, which material is typically used as a moderator?
Uranium
Graphite
Plutonium
Lead
Explanation - Graphite slows down neutrons to sustain a controlled chain reaction in a nuclear reactor.
Correct answer is: Graphite
Q.21 Binding energy per nucleon is maximum for which element?
Hydrogen
Iron
Uranium
Lead
Explanation - Iron-56 has the highest binding energy per nucleon, making it the most stable nucleus.
Correct answer is: Iron
Q.22 Which type of radiation is used in cancer radiotherapy?
Alpha rays
Beta rays
Gamma rays
Neutrinos
Explanation - Gamma rays penetrate tissue and destroy cancer cells, making them ideal for radiotherapy.
Correct answer is: Gamma rays
Q.23 Which property distinguishes isotopes of an element?
Number of protons
Number of neutrons
Number of electrons
Atomic number
Explanation - Isotopes have the same number of protons but different numbers of neutrons.
Correct answer is: Number of neutrons
Q.24 Which phenomenon occurs when a nucleus absorbs a neutron and becomes unstable?
Nuclear fusion
Nuclear fission
Radioactive decay
Nuclear scattering
Explanation - Absorption of a neutron by a heavy nucleus like Uranium-235 can trigger fission, splitting the nucleus and releasing energy.
Correct answer is: Nuclear fission
Q.25 Which decay does not change the atomic number of the nucleus?
Alpha decay
Beta minus decay
Gamma decay
Beta plus decay
Explanation - Gamma decay involves emission of energy only, so the atomic number and mass number remain unchanged.
Correct answer is: Gamma decay