TRUE OR FALSE — INTRODUCTION TO CHEMISTRY, SCIENTIFIC METHOD AND ATOMS
Chemistry & Its Branches
1. Chemistry
Statement 1: Chemistry is the scientific discipline that focuses on the study of matter, its composition, structure and properties.
ANSWER: True
Statement 2: Chemistry has no connection to fields like physics, biology or environmental science.
ANSWER: False — Chemistry intersects with fields like physics, biology and environmental science.
Statement 3: Chemistry plays a role in developing new technologies, materials and drugs.
ANSWER: True
2. Physical Chemistry
Statement 1: Physical chemistry combines principles from physics and chemistry to study the relationship between a substance's physical properties and its chemical composition.
ANSWER: True
Statement 2: Physical chemistry is a branch of applied chemistry, not pure chemistry.
ANSWER: False — It is one of the three branches of pure chemistry, alongside organic and inorganic chemistry.
Statement 3: Physical chemistry is one of three branches of pure chemistry.
ANSWER: True
3. Organic Chemistry
Statement 1: Organic chemistry studies carbon-based molecules, their properties, composition and reactions.
ANSWER: True
Statement 2: Organic chemistry studies non-carbon-based compounds.
ANSWER: False — That describes inorganic chemistry.
Statement 3: Organic chemistry is a branch of pure chemistry.
ANSWER: True
4. Inorganic Chemistry
Statement 1: Inorganic chemistry studies non-carbon-based compounds, including the properties of elements and their compounds.
ANSWER: True
Statement 2: Inorganic chemistry studies carbon-based molecules.
ANSWER: False — That describes organic chemistry.
Statement 3: Inorganic chemistry is one of the three branches of pure chemistry.
ANSWER: True
5. Pure Chemistry
Statement 1: Pure chemistry studies the basic principles and theories of chemistry without considering practical use.
ANSWER: True
Statement 2: Physical, organic and inorganic chemistry are all branches of pure chemistry.
ANSWER: True
Statement 3: Pure chemistry focuses mainly on solving real-world problems using scientific methods.
ANSWER: False — That describes applied chemistry.
6. Applied Chemistry
Statement 1: Applied chemistry studies the practical applications of chemical knowledge to solve real-world problems.
ANSWER: True
Statement 2: Applied chemistry has applications in food science, medicine, pharmaceuticals and agriculture.
ANSWER: True
Statement 3: Applied chemistry is concerned only with theories, not with practical use.
ANSWER: False — That describes pure chemistry; applied chemistry is about practical application.
Chemical Hazards
7. Explosives
Statement 1: Explosives can rapidly release energy in the form of heat, light, gas and sound.
ANSWER: True
Statement 2: Dynamite and ammonium nitrate are examples of explosives.
ANSWER: True
Statement 3: Explosives cannot cause physical damage or injury.
ANSWER: False — Their rapid release of energy can cause physical damage and injury.
8. Flammable liquids and gases
Statement 1: Flammable liquids and gases can ignite or explode when exposed to heat, sparks or flames.
ANSWER: True
Statement 2: Gasoline, propane and cooking oils are examples of flammable liquids and gases.
ANSWER: True
Statement 3: Flammable substances are incapable of causing fires.
ANSWER: False — They can cause burns, fires and explosions.
9. Corrosive substances
Statement 1: Corrosive substances can destroy or damage materials such as metals, plastics or human tissue.
ANSWER: True
Statement 2: Hydrochloric acid and sodium hydroxide are examples of corrosive substances.
ANSWER: True
Statement 3: Corrosive substances are incapable of causing severe burns.
ANSWER: False — They can cause severe burns and tissue damage.
10. Toxic substances
Statement 1: Toxic substances can harm or kill living organisms by interfering with biological functions.
ANSWER: True
Statement 2: Arsenic, lead and cyanide are examples of toxic substances.
ANSWER: True
Statement 3: Toxic substances have no effect on vital organ systems.
ANSWER: False — They disrupt vital organ systems.
11. Oxidising substances
Statement 1: Oxidising substances can accelerate and promote combustion in other materials by providing oxygen.
ANSWER: True
Statement 2: Hydrogen peroxide and potassium permanganate are examples of oxidising substances.
ANSWER: True
Statement 3: Oxidising substances cannot cause burns or explosions.
ANSWER: False — They can cause severe burns, respiratory damage and explosions.
12. Radioactive substances
Statement 1: Radioactive substances spontaneously emit radiation as a result of the decay of atomic nuclei.
ANSWER: True
Statement 2: Uranium and cobalt-60 are examples of radioactive substances.
ANSWER: True
Statement 3: Proper handling and disposal of radioactive substances is unnecessary.
ANSWER: False — Proper handling and disposal are essential due to the risk of radiation exposure.
13. Irritant substances
Statement 1: Irritant substances can cause irritation or inflammation on contact with the skin, eyes or respiratory system.
ANSWER: True
Statement 2: Ammonia and detergents are examples of irritant substances.
ANSWER: True
Statement 3: Irritant substances cannot cause itching, redness or swelling.
ANSWER: False — They can cause itching, pain, redness, swelling and blistering.
14. Harmful substances
Statement 1: Harmful substances can pose a risk to health and safety, causing acute or chronic effects depending on dose and duration.
ANSWER: True
Statement 2: Lead, asbestos and tobacco smoke are examples of harmful substances.
ANSWER: True
Statement 3: The effects of harmful substances never depend on dose or duration of exposure.
ANSWER: False — Their effects depend on the dose, duration and mode of exposure.
15. Biohazard substances
Statement 1: Biohazard substances can pose a threat to the health and safety of living organisms.
ANSWER: True
Statement 2: Blood, bodily fluids and microorganisms are examples of biohazard substances.
ANSWER: True
Statement 3: Biohazard substances never contain living or non-living biological agents.
ANSWER: False — They may contain living and non-living biological agents such as bacteria, viruses and toxins.
Safety Equipment
16. A fire blanket
Statement 1: A fire blanket is designed to extinguish incipient, or starting, fires.
ANSWER: True
Statement 2: A fire blanket should be used by holding its corner and covering the fire from its base.
ANSWER: True
Statement 3: A fire blanket should be removed as soon as it touches the fire.
ANSWER: False — It should stay in place until the fire has completely stopped.
17. A fire extinguisher
Statement 1: A fire extinguisher is usually filled with a dry or wet chemical.
ANSWER: True
Statement 2: The acronym PASS describes the steps for using a fire extinguisher: Pull, Aim, Squeeze, Sweep.
ANSWER: True
Statement 3: A fire extinguisher is a fixed device that cannot be handheld.
ANSWER: False — It is a handheld active fire protection device.
18. Personal Protective Equipment (PPE)
Statement 1: Respirators, hand gloves, eye protectors and protective clothing are all examples of PPE.
ANSWER: True
Statement 2: A lab coat and safety goggles are common examples of PPE in a chemistry laboratory.
ANSWER: True
Statement 3: PPE is designed to protect only the environment, not the wearer.
ANSWER: False — PPE is designed to protect the wearer from injury, illness or death.
19. Eye shower station
Statement 1: An eye shower station provides immediate treatment to someone who has had contact with hazardous materials in the eye.
ANSWER: True
Statement 2: An eye shower station consists of a basin attached to a water supply.
ANSWER: True
Statement 3: An eye shower station is a type of protective clothing.
ANSWER: False — It is a safety device, not a piece of protective clothing.
20. Fume chamber (fume hood)
Statement 1: A fume chamber is designed to contain and capture hazardous fumes, dust or vapours.
ANSWER: True
Statement 2: A fume chamber helps prevent contamination of the external environment.
ANSWER: True
Statement 3: A fume chamber is an open bench with no enclosure.
ANSWER: False — It is an enclosed space or hood, not an open bench.
Scientific Method & Related Concepts
21. The scientific method
Statement 1: The scientific method is used to investigate the natural world in a logical, objective and repeatable manner.
ANSWER: True
Statement 2: Communicating results is the final step of the scientific method.
ANSWER: True
Statement 3: Making observations and formulating a hypothesis come after communicating results in the scientific method.
ANSWER: False — Observations and hypothesis formulation happen early; communication is the final step.
22. A hypothesis
Statement 1: A hypothesis is a testable explanation designed to guide experimentation.
ANSWER: True
Statement 2: A hypothesis is formed after observations have been made and a question has been asked.
ANSWER: True
Statement 3: A hypothesis is a proven fact.
ANSWER: False — A hypothesis is an educated guess, not yet a proven fact.
23. A scientific theory
Statement 1: A scientific theory is based on experimental data.
ANSWER: True
Statement 2: A scientific theory has already been extensively tested and supported by evidence.
ANSWER: True
Statement 3: A scientific theory is merely a guess with no supporting evidence.
ANSWER: False — Unlike a hypothesis, a theory is well-established and supported by evidence.
24. A scientific law
Statement 1: A scientific law is often represented by a mathematical formula.
ANSWER: True
Statement 2: A scientific law describes what happens rather than explaining the underlying cause.
ANSWER: True
Statement 3: A scientific law explains why something happens rather than describing what happens.
ANSWER: False — A theory explains why; a law describes what happens.
Dalton & Atomic Theory
25. Atomic theory
Statement 1: Atomic theory states that elements are made up of atoms.
ANSWER: True
Statement 2: Several scientists, including Dalton, Thomson and Rutherford, contributed to the modern form of atomic theory.
ANSWER: True
Statement 3: Atomic theory was developed in a single year by a single scientist.
ANSWER: False — Its development spans centuries of scientific discovery.
26. Dalton's atomic theory
Statement 1: Dalton's atomic theory states that atoms of the same element are identical, while atoms of different elements differ.
ANSWER: True
Statement 2: All of Dalton's original postulates have remained unmodified by later discoveries.
ANSWER: False — Some postulates, such as atoms being indivisible, have since been modified by discoveries like isotopes.
Statement 3: Dalton's atomic theory states that all elements are made up of small, indivisible particles.
ANSWER: True
27. Isotopes
Statement 1: Isotopes share the same number of protons but have different numbers of neutrons.
ANSWER: True
Statement 2: A carbon atom can have 6, 7 or 8 neutrons while remaining an example of isotopes.
ANSWER: True
Statement 3: The existence of isotopes fully supports every one of Dalton's original postulates.
ANSWER: False — Isotopes contradict Dalton's postulate that all atoms of an element are identical.
J.J. Thomson
28. The cathode ray experiment
Statement 1: The cathode ray experiment involved passing an electric current through a vacuum tube.
ANSWER: True
Statement 2: The cathode ray experiment revealed a stream of negatively charged particles travelling from the cathode to the anode.
ANSWER: True
Statement 3: The cathode ray experiment provided no evidence relevant to the discovery of the electron.
ANSWER: False — It laid the foundation for the discovery of the electron.
29. Electron
Statement 1: The electron carries a negative charge and is located outside the nucleus.
ANSWER: True
Statement 2: The electron's charge-to-mass ratio was found to be much smaller than any known atom.
ANSWER: True
Statement 3: The electron was discovered before the cathode ray experiments were conducted.
ANSWER: False — The electron was discovered by studying the particles that made up cathode rays.
30. The plum pudding model
Statement 1: The plum pudding model describes the atom as a positively charged sphere with negatively charged particles embedded within it.
ANSWER: True
Statement 2: The plum pudding model was developed based on the discovery of the electron.
ANSWER: True
Statement 3: The plum pudding model was never disproved by later experiments.
ANSWER: False — It was later disproved by the discovery of the atomic nucleus.
Rutherford
31. The gold foil (alpha scattering) experiment
Statement 1: The gold foil experiment involved firing positively charged alpha particles at a thin sheet of gold foil.
ANSWER: True
Statement 2: In the gold foil experiment, most particles passed straight through, though a few bounced backward.
ANSWER: True
Statement 3: The gold foil experiment provided no evidence for the existence of the atomic nucleus.
ANSWER: False — Its results provided evidence for the existence of the atomic nucleus.
32. Rutherford's nuclear model
Statement 1: Rutherford's nuclear model introduced the concept of a small, dense, positively charged nucleus at the centre of the atom.
ANSWER: True
Statement 2: In Rutherford's nuclear model, electrons orbit the nucleus in specific paths, similar to planets orbiting the sun.
ANSWER: True
Statement 3: Rutherford's nuclear model successfully explained why electrons don't spiral into the nucleus.
ANSWER: False — It was unable to explain this.
33. The atomic nucleus
Statement 1: The atomic nucleus is small, dense and positively charged.
ANSWER: True
Statement 2: The atomic nucleus contains most of the mass of the atom.
ANSWER: True
Statement 3: The atomic nucleus is surrounded by positively charged electrons.
ANSWER: False — Electrons are negatively charged, not positively charged.
Subatomic Particles
34. Proton
Statement 1: The proton carries a positive charge.
ANSWER: True
Statement 2: The proton's relative mass is 1 atomic mass unit.
ANSWER: True
Statement 3: The proton is found outside the nucleus of an atom.
ANSWER: False — The proton is found within the nucleus, alongside the neutron.
35. Neutron
Statement 1: The neutron carries no charge at all.
ANSWER: True
Statement 2: The neutron's relative mass is the same as the proton's, 1 atomic mass unit.
ANSWER: True
Statement 3: The neutron carries a negative charge.
ANSWER: False — The neutron is neutral; it carries no charge.
Bohr's Theory
36. Bohr's planetary theory
Statement 1: Bohr's planetary theory states that electrons orbit the nucleus in fixed, circular orbits at specific energy levels.
ANSWER: True
Statement 2: Bohr's planetary theory introduced the concepts of ground state and excited state.
ANSWER: True
Statement 3: Under Bohr's planetary theory, electrons can occupy any energy level, not just specific quantised states.
ANSWER: False — Energy levels are quantised; electrons can only occupy specific states.
37. Ground state
Statement 1: Ground state describes an electron orbiting the nucleus at its lowest possible energy level.
ANSWER: True
Statement 2: An electron only leaves the ground state by absorbing energy.
ANSWER: True
Statement 3: Ground state is the same as an excited state.
ANSWER: False — Ground state is the opposite of an excited state.
38. Excited state
Statement 1: Excited state describes an electron that has absorbed energy and jumped to a higher energy level.
ANSWER: True
Statement 2: An electron eventually returns from an excited state to its ground state, releasing energy in the process.
ANSWER: True
Statement 3: The energy released as an electron leaves an excited state has no relationship to the wavelength of light emitted.
ANSWER: False — The energy released corresponds to a specific wavelength of light.
39. Continuous spectrum
Statement 1: A continuous spectrum contains photons of all energy levels within a specific range.
ANSWER: True
Statement 2: A hot solid object, such as a light bulb filament, is an example of a source that produces a continuous spectrum.
ANSWER: True
Statement 3: A continuous spectrum appears as a series of discrete lines rather than a smooth display.
ANSWER: False — That describes a line spectrum; a continuous spectrum appears as a smooth display of colours.
40. Line spectrum
Statement 1: A line spectrum is produced by an excited atom or molecule.
ANSWER: True
Statement 2: Each chemical element has its own unique line spectrum.
ANSWER: True
Statement 3: A line spectrum contains a continuous range of wavelengths rather than discrete lines.
ANSWER: False — A line spectrum contains only discrete wavelengths or colours.
Quantum Theory
41. Wave-particle duality
Statement 1: Wave-particle duality suggests that particles can exhibit both wave-like and particle-like behaviours.
ANSWER: True
Statement 2: Electrons exhibit both a particle-like and a wave-like nature because of wave-particle duality.
ANSWER: True
Statement 3: Wave-particle duality was rejected by quantum theory.
ANSWER: False — Quantum theory introduced this concept to help explain electron behaviour.
42. The uncertainty principle
Statement 1: The uncertainty principle states that it is impossible to know both the position and the momentum of an electron at the same time.
ANSWER: True
Statement 2: The uncertainty principle places a fundamental limit on how precisely certain properties can be known simultaneously.
ANSWER: True
Statement 3: The uncertainty principle allows a scientist to know both the position and momentum of an electron with complete precision.
ANSWER: False — It states this is impossible.
43. Principal quantum number (n)
Statement 1: The principal quantum number determines the energy level of an electron.
ANSWER: True
Statement 2: The principal quantum number can have any positive value starting from 1.
ANSWER: True
Statement 3: The principal quantum number describes the shape of the electron cloud.
ANSWER: False — That is described by the angular momentum (azimuthal) quantum number.
44. Angular momentum (azimuthal) quantum number (l)
Statement 1: The angular momentum quantum number indicates the shape of the electron cloud, or subshell.
ANSWER: True
Statement 2: The angular momentum quantum number can have a value from 0 to one less than the principal quantum number.
ANSWER: True
Statement 3: The angular momentum quantum number describes the spin of an electron.
ANSWER: False — That is described by the spin quantum number.
45. Magnetic quantum number (m)
Statement 1: The magnetic quantum number specifies the orientation of the electron cloud in space.
ANSWER: True
Statement 2: The magnetic quantum number can have values ranging from negative to positive versions of the angular momentum quantum number.
ANSWER: True
Statement 3: The magnetic quantum number determines the energy level of an electron.
ANSWER: False — That is described by the principal quantum number.
46. Spin quantum number (s)
Statement 1: The spin quantum number describes the spin of an electron.
ANSWER: True
Statement 2: The spin quantum number can only have one of two possible values, positive or negative one-half.
ANSWER: True
Statement 3: The spin quantum number can take any value between 0 and the principal quantum number.
ANSWER: False — It can only be positive or negative one-half.
47. The s orbital
Statement 1: The s orbital has a spherical shape.
ANSWER: True
Statement 2: The s orbital can hold up to two electrons.
ANSWER: True
Statement 3: The s orbital has a dumb-bell shape.
ANSWER: False — That describes the p orbital; the s orbital is spherical.
48. The p orbital(s)
Statement 1: The p orbitals have a dumb-bell shape.
ANSWER: True
Statement 2: The p orbitals come in three versions, aligned along perpendicular axes, and together hold up to six electrons.
ANSWER: True
Statement 3: The p orbitals can hold up to ten electrons in total.
ANSWER: False — The p orbitals hold up to six electrons; ten is the capacity of the d orbitals.
49. The d orbital(s)
Statement 1: The d orbitals have more complex shapes than the s and p orbitals.
ANSWER: True
Statement 2: The d orbitals are found in the third energy level and higher, and can hold up to ten electrons together.
ANSWER: True
Statement 3: The d orbitals are the lowest-energy, simplest-shaped orbitals.
ANSWER: False — The s orbital is the lowest and simplest; d orbitals are more complex.
Electron Filling Rules
50. Aufbau's principle
Statement 1: Aufbau's principle states that atomic orbitals are filled with electrons in order of increasing energy.
ANSWER: True
Statement 2: Aufbau's principle is used to determine the electron configuration of atoms.
ANSWER: True
Statement 3: Aufbau's principle states that electrons fill higher energy orbitals before lower ones.
ANSWER: False — Electrons fill lower energy orbitals first.
51. Pauli's exclusion principle
Statement 1: Pauli's exclusion principle states that no two electrons in an atom can have the same set of quantum numbers.
ANSWER: True
Statement 2: Pauli's exclusion principle requires two electrons sharing an orbital to have opposite spins.
ANSWER: True
Statement 3: Pauli's exclusion principle allows unlimited electrons to occupy a single orbital.
ANSWER: False — It limits the number of electrons that can occupy any single orbital.
52. Hund's rule of maximum multiplicity
Statement 1: Hund's rule states that electrons will occupy orbitals singly, with parallel spins, before they pair up.
ANSWER: True
Statement 2: Under Hund's rule, electron pairing in p and d orbitals cannot occur until each orbital in the subshell holds one electron.
ANSWER: True
Statement 3: Hund's rule states that electrons must pair up in the same orbital before occupying other orbitals in the subshell.
ANSWER: False — Electrons occupy orbitals singly first, before pairing up.
Mass Concepts
53. Relative atomic mass
An element has two isotopes with mass numbers 10 and 15. The abundance of the mass-10 isotope is $80\%$ and the abundance of the mass-15 isotope is $20\%$.
Statement 1: The contribution of the mass-10 isotope to the weighted average is 8.0.
ANSWER: True — $10 \times 0.80 = 8.0$.
Statement 2: The contribution of the mass-15 isotope to the weighted average is 4.0.
ANSWER: False — $15 \times 0.20 = 3.0$, not 4.0.
Statement 3: The relative atomic mass of the element works out to 11.
ANSWER: True — $A_r = 8.0 + 3.0 = 11$ (2 s.f., matching the 2 s.f. abundances given).
54. Relative molecular mass
Statement 1: Relative molecular mass is the sum of the relative atomic masses of all the atoms in a molecule.
ANSWER: True
Statement 2: Relative molecular mass is measured relative to the mass of carbon-12.
ANSWER: True
Statement 3: Relative molecular mass ignores how many atoms of each element are present in a molecule.
ANSWER: False — It is calculated by adding up the atomic masses of every atom present, considering how many of each are in the molecule.
55. A mass spectrometer
Statement 1: A mass spectrometer is used for measuring the mass-to-charge ratio of ions in a sample.
ANSWER: True
Statement 2: A mass spectrometer generates ions from a sample, then separates them using electric and magnetic fields.
ANSWER: True
Statement 3: A mass spectrometer is used only in chemistry, with no application in biochemistry or environmental science.
ANSWER: False — It is used across chemistry, biochemistry, physics, geology and environmental science.
56. A mass spectrum
Statement 1: A mass spectrum shows ion intensities as a function of their mass-to-charge ratios.
ANSWER: True
Statement 2: The height of each peak in a mass spectrum is proportional to the abundance of that ion.
ANSWER: True
Statement 3: A mass spectrum shows a single peak for every sample, regardless of its isotopes.
ANSWER: False — It shows a series of peaks, each representing an ion with a specific mass-to-charge ratio.
Radioactivity
57. Radioactivity
Statement 1: Radioactivity involves the emission of energy from an unstable nucleus, either as particles or electromagnetic radiation.
ANSWER: True
Statement 2: Radioactivity has practical applications in medicine, industry and energy production.
ANSWER: True
Statement 3: Radioactivity poses no health risks or safety concerns.
ANSWER: False — It poses health risks and safety concerns that require careful management.
58. A radioisotope
Statement 1: A radioisotope is also referred to as a radionuclide.
ANSWER: True
Statement 2: A radioisotope decays at a fixed rate, characterised by a half-life.
ANSWER: True
Statement 3: Every radioisotope shares exactly the same rate of decay.
ANSWER: False — Each radioisotope's rate of decay is unique to that isotope.
59. Half-life
A radioisotope has an initial activity of $80\ \text{Bq}$ and a final activity of $10\ \text{Bq}$. This sample was left for $18$ years.
Statement 1: The activity of 80 Bq must halve three times to reach 10 Bq $(80 \rightarrow 40 \rightarrow 20 \rightarrow 10)$.
ANSWER: True
Statement 2: The activity would already reach 10 Bq after only two half-lives.
ANSWER: False — After two halvings, $80 \rightarrow 40 \rightarrow 20\ \text{Bq}$, not 10 Bq; a third halving is needed.
Statement 3: Given this data, the half-life of the sample works out to 6.0 years.
ANSWER: True — $t_{1/2} = \dfrac{18\ \text{years}}{3\ \text{half-lives}} = 6.0\ \text{years}$ (2 s.f., matching the 2 s.f. data given).
60. Alpha radiation
Statement 1: Alpha radiation consists of a helium nucleus, made of two protons and two neutrons.
ANSWER: True
Statement 2: Alpha radiation can be blocked by a sheet of paper or the dead cells on the surface of skin.
ANSWER: True
Statement 3: Alpha radiation carries no charge at all.
ANSWER: False — Alpha radiation has a charge of positive two.
61. Beta radiation
Statement 1: Beta radiation consists of a negatively charged particle identical to a high-energy electron.
ANSWER: True
Statement 2: Beta radiation is more penetrating than alpha particles, able to pass through several millimetres of aluminium.
ANSWER: True
Statement 3: Beta radiation has a negligible charge but a large mass.
ANSWER: False — Beta radiation has a charge of negative one and a negligible mass.
62. Gamma radiation
Statement 1: Gamma radiation consists of high-energy photons of electromagnetic radiation.
ANSWER: True
Statement 2: Gamma radiation is highly penetrating, able to pass through several centimetres of lead or concrete.
ANSWER: True
Statement 3: Gamma radiation has both charge and mass.
ANSWER: False — Gamma radiation has no charge and no mass.
63. Neutron-to-proton ratio
Statement 1: The neutron-to-proton ratio describes the balance between the number of neutrons and protons in a nucleus.
ANSWER: True
Statement 2: For light isotopes, a stable neutron-to-proton ratio tends to be close to one.
ANSWER: True
Statement 3: A nucleus is always stable regardless of its neutron-to-proton ratio.
ANSWER: False — When the ratio is too low or too high, the resulting nucleus tends to be unstable.
64. Binding energy per nucleon
Statement 1: Binding energy per nucleon refers to the average energy required to remove a nucleon from the nucleus.
ANSWER: True
Statement 2: Binding energy per nucleon is calculated by dividing the total binding energy of a nucleus by its total number of nucleons.
ANSWER: True
Statement 3: A low binding energy per nucleon generally indicates a more stable nucleus.
ANSWER: False — A high value generally indicates a more stable nucleus.
65. A nuclear reaction
Statement 1: A nuclear reaction involves changes in the atomic nuclei of the reacting substances.
ANSWER: True
Statement 2: A nuclear reaction involves much larger energy changes than a chemical reaction.
ANSWER: True
Statement 3: A nuclear reaction results in exactly the same nuclei and particles as before the reaction.
ANSWER: False — It results in the formation of different nuclei and subatomic particles.
Uses & Risks of Radioactivity
66. Medical diagnosis (using radioisotopes)
Statement 1: Technetium-99, iodine-131 and gallium-67 are radioisotopes used for medical diagnosis.
ANSWER: True
Statement 2: Techniques like PET, SPECT and CT scans rely on radioisotopes emitting gamma rays that special cameras can detect.
ANSWER: True
Statement 3: Medical diagnosis using radioisotopes cannot help monitor diseases such as cancer or heart disease.
ANSWER: False — It allows doctors to diagnose and monitor such diseases.
67. Medical treatment (using radioisotopes)
Statement 1: Iodine-131 is used to treat thyroid cancer.
ANSWER: True
Statement 2: Strontium-89 is used to relieve pain in bone cancer patients.
ANSWER: True
Statement 3: Medical treatment using radioisotopes has the same goal as diagnostic uses, namely imaging rather than destruction of diseased tissue.
ANSWER: False — Its goal is destruction of diseased tissue, unlike diagnostic uses.
68. Industrial applications (of radioisotopes)
Statement 1: Cobalt-60 and iridium-192 are radioisotopes used for industrial applications.
ANSWER: True
Statement 2: Industrial applications of radioisotopes include sterilising medical equipment and food products.
ANSWER: True
Statement 3: Industrial applications of radioisotopes never involve measuring the thickness of materials.
ANSWER: False — They also include measuring the thickness of materials during manufacturing.
69. Agricultural applications (of radioisotopes)
Statement 1: Agricultural applications of radioisotopes involve measuring plant and soil properties, such as moisture content and nutrient uptake.
ANSWER: True
Statement 2: Radioisotopes used in agriculture are also applied in insect and pest control.
ANSWER: True
Statement 3: Agricultural applications of radioisotopes have no effect on crop yield or quality.
ANSWER: False — They help improve crop yield and quality.
70. Radiation exposure
Statement 1: Radiation exposure can damage the DNA in cells, leading to cellular mutations and cancer.
ANSWER: True
Statement 2: High levels of radiation exposure can cause sickness and death.
ANSWER: True
Statement 3: Long-term exposure to low levels of radiation carries no increased risk of cancer.
ANSWER: False — Long-term exposure to low levels is associated with an increased risk of cancer.