Free Composition of Atomic Nuclei MCQs with Answers
100 Composition of Atomic Nuclei MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Atomic nuclei contain positively charged protons and electrically neutral neutrons, collectively called nucleons. Questions use atomic number, mass number and nuclear notation to identify isotopes, isobars and isotones, and may connect nuclear composition with nuclear charge, mass defect, binding energy and the stability of the nucleus.
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- A. number of neutrons but different numbers of protons
- B. number of protons but different numbers of neutrons
- C. mass number but different atomic numbers
- D. number of protons and neutrons
Explanation: Atomic number fixes the element, so isotopes share chemical behaviour but differ in mass, as carbon 12 and carbon 14 do.
Correct answer: number of protons but different numbers of neutrons- A. 92
- B. 143
- C. 235
- D. 327
Explanation: Neutron number is mass number minus atomic number, so 235 minus 92 gives 143.
Correct answer: 143- A. the electrostatic force
- B. the gravitational force
- C. the strong nuclear force, which is short ranged and attractive
- D. the magnetic force
Explanation: The strong force acts over only a few femtometres but is far stronger than the electrostatic repulsion between protons at that range…
Correct answer: the strong nuclear force, which is short ranged and attractive- A. two light nuclei join to form a heavier one
- B. a heavy nucleus splits into two lighter nuclei, releasing energy and neutrons
- C. a nucleus emits an alpha particle
- D. an electron is captured by a nucleus
Explanation: Splitting a uranium 235 nucleus releases about 200 MeV together with two or three neutrons, and those neutrons can trigger further…
Correct answer: a heavy nucleus splits into two lighter nuclei, releasing energy and neutrons- A. absorb excess neutrons and shut the reactor down
- B. slow fast neutrons so that they are more likely to cause further fission
- C. cool the reactor core
- D. shield the operators from radiation
Explanation: Graphite or heavy water slows the neutrons through repeated collisions, because slow neutrons are far more readily captured by uranium 235…
Correct answer: slow fast neutrons so that they are more likely to cause further fission- A. the chemical bonds between atoms
- B. the small loss of mass, converted according to E equals mc squared
- C. the kinetic energy of the electrons
- D. friction inside the nucleus
Explanation: The products of fission or fusion have slightly less total mass than the reactants, and that mass defect appears as energy, which is why…
Correct answer: the small loss of mass, converted according to E equals mc squared- A. hydrogen
- B. iron
- C. uranium
- D. helium
Explanation: The curve of binding energy per nucleon rises steeply from hydrogen, peaks around iron and nickel at about 8.8 MeV, then falls slowly…
Correct answer: iron- A. uranium into lead
- B. hydrogen into helium
- C. helium into hydrogen
- D. carbon into oxygen
Explanation: Four hydrogen nuclei combine through the proton proton chain to give one helium nucleus, and the small mass difference appears as energy.
Correct answer: hydrogen into helium- A. Electromagnetic force
- B. Gravitational force
- C. Weak nuclear force
- D. Strong nuclear force
Explanation: The strong nuclear force acts over only a few femtometres but far exceeds the electrostatic repulsion between protons at that range, so it…
Correct answer: Strong nuclear force- A. Proton
- B. Meson
- C. Neutron
- D. Positron
Explanation: The electron's antiparticle is the positron, which has the same mass as an electron but an equal positive charge instead of a negative…
Correct answer: Positron- A. 1 gram
- B. 1 Kg
- C. 100 Kg
- D. None
Explanation: The platinum-iridium cylinder kept near Paris was the historical international prototype of the kilogram, so its standard mass was 1 kg.
Correct answer: 1 Kg- A. Anti-electrons
- B. Anti-proton
- C. Anti-neutron
- D. All of these
Explanation: Antimatter contains antiparticles, including positrons or anti-electrons, antiprotons and antineutrons, each having opposite relevant…
Correct answer: All of these- A. Chadwick
- B. Rutherford
- C. Neil Bohr
- D. Einstein
Explanation: James Chadwick discovered the neutron in 1932 by showing that penetrating radiation from beryllium consisted of neutral particles with…
Correct answer: Chadwick- A. massive nucleus join together
- B. massive nucleus splits to form smaller fragments
- C. both A & B
- D. None of these
Explanation: In nuclear fission, a heavy or massive nucleus splits into two or more smaller nuclei, releasing energy and usually neutrons.
Correct answer: massive nucleus splits to form smaller fragments- A. Moderators slow down the neutrons
- B. Moderators bring the neutrons to rest
- C. Moderators absorb the neutrons
- D. Moderators reflect the neutrons
Explanation: A moderator reduces the kinetic energy of fast neutrons through repeated collisions, bringing them to thermal energies suitable for…
Correct answer: Moderators slow down the neutrons- A. 18.336
- B. 1836
- C. 18360
- D. 183.6
Explanation: The weight ratio is approximately the mass ratio because both objects experience the same gravitational acceleration: Wh/We = mhg/meg =…
Correct answer: 1836- A. Plus one
- B. Plus two
- C. Minus two
- D. Minus one
Explanation: An alpha particle is a helium nucleus containing two protons and two neutrons, so its net charge is +2 elementary charges, written +2e.
Correct answer: Plus two- A. 92U235
- B. 92U238
- C. 92U234
- D. 92U239
Explanation: A liquid-metal fast breeder reactor uses uranium-238 as fertile material, which absorbs fast neutrons and can ultimately form…
Correct answer: 92U238- A. Heat energy is released
- B. Nuclear energy is released
- C. Chemical energy is released
- D. Light energy is released
Explanation: During fission, the combined mass of the products is slightly less than the original nuclear mass, and the mass difference is released as…
Correct answer: Nuclear energy is released- A. Smaller
- B. Greater than 82
- C. Same
- D. Sometimes smaller some times greater
Explanation: The separate nucleons have slightly greater total mass than the bound nucleus; the difference is the mass defect and corresponds to…
Correct answer: Greater than 82Composition of Atomic Nuclei MCQs: common questions
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