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HSC Chemistry 9.2.5 Production of Materials Example Questions
Markers comments and marking guidelines
Example Question 1: (2012 HSC Chemistry exam) Question 27 (3 marks)
Markers’ Comments:
(a) In better responses, candidates linked the uses of both Iodine-123 and Iodine-131 with
the type of radiation each emitted. They indicated that the Iodine-123 and Iodine-131
concentrated in areas of the body where gamma rays, which have high penetration of
biological tissue, could be detected outside the body by a gamma ray detector/scanner,
providing a diagnostic image of the organ. Such responses also linked Iodine-131 as a beta
particle emitter, which has a low ability to penetrate biological tissue, and hence can be
used to destroy cancer cells close to where they are inside the body.
In weaker responses, candidates tended to repeat the information in the question, referring
to either gamma or beta emission. In some responses, candidates compared the energy or
penetration of both types of radiation using the information provided in the question, or
included general comments about beta particles and gamma rays causing damage to cells.
(b) In better responses, candidates included a correctly balanced nuclear equation with
mass numbers on the top left-hand side of the element symbol and atomic numbers on the
bottom left-hand side of the symbol. The mass numbers and atomic numbers were added
correctly on both sides of the equation.
In weaker responses, candidates did not correctly show beta particles in an equation, used
an incorrect notation for a beta particle, or included the beta particle on the wrong side of
the equation. In many responses, candidates failed to recognise that a change in atomic
number resulted in a change of element.
Sample answers:
a) As ß-particles do not travel far through tissue, they transfer their energy to cells near to
the source of the radiation, killing nearby cells. This means that a ß-emitter can be used for
therapy, but as the radiation cannot be detected outside the body, it is of little use in
determining where a radioisotope has been transported to. On the other hand, X-rays easily
travel outside the body, so an γ-emitter can be used to determine where an isotope has
been transported to, hence it is useful for diagnosis. Relatively little of the energy is
transformed to nearby tissue, so an internal γ-emitter is not appropriate for killing targeted
cells.
b)
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HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines
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Markers’ guidelines Question 27 (a)
Criteria
Marks
• Justifies the different uses of the radioisotopes, by demonstrating an
understanding of penetration and energy transfer for both types of
emission
2
• Justifies the different uses of the radioisotopes, by demonstrating an
understanding of penetration or energy transfer for ONE type of emission
or a partial understanding of both types
1
Markers’ guidelines Question 27 (b)
Criteria
Correct equation is given
Marks
1
2
HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines
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Example Question 2: (2011 HSC Chemistry exam) Question 23 (3 marks)
Markers’ Comments:
a. In better responses, candidates recognised that Cn-278 is unstable because of the
size/mass of the nucleus. In weaker responses, candidates referred to the
proton/neutron ratio or confused instability with being transuranic. Some responses
displayed confusion between stability and reactivity.
b. In better responses, candidates described the process whereby transuranic isotopes
are synthesised in nuclear reactors or particle accelerators. Some candidates included
examples of relevant nuclear equations. In weaker responses, the process of
transuranic isotope formation was not correctly paired with the location of the process.
Many responses were vague on the nature of the particles interacting with the large
nuclei and the speed or method of interaction.
Sample answers:
a) Isotopes such as copernicium-278 are unstable because they are heavy nuclei with high
neutron:proton ratios, eg Cn-278 = 166:112.
b) Transuranic elements can be synthesised in a particle accelerator (positive ion
accelerator). There are three types of accelerators: linear accelerators, cyclotrons and
synchrotrons. Each uses alternating electric and magnetic fields to accelerate particles at
high speed to penetrate a target nucleus.
Answers could include:
Bombardment with neutrons, which occurs in a nuclear reactor, as no acceleration is
necessary for neutrons to be absorbed by a target nucleus
Markers’ guidelines Question 23 (a)
Outcomes assessed H6, H14
Criteria
Gives ONE correct reason why an isotope such as copernicium-278 is
unstable
Marks
1
Markers’ guidelines Question 23 (b)
Outcomes assessed H6, H12
Criteria
Marks
Provides features of a method by which transuranic elements can be
synthesised
2
Identifies a correct method by which transuranic elements can be
synthesised
1
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HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines
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Example Question 3: (2007 HSC Chemistry exam) Question 19 (7 marks)
Markers’ Comments:
In the better responses, candidates demonstrated a thorough knowledge of both the
characteristics of the respective radioisotopes and provided a link as to how these properties
related to their use. Better responses included an appropriate evaluation. They also showed
evidence of planning to ensure all aspects of the holistic question were attempted.
Outcomes assessed: H4,H8, H14
Markers’ guidelines Question 19
Criteria
Marks
Demonstrates a thorough knowledge and understanding of a named
radioisotope and its use in industry and a named radioisotope and its use in
medicine
Describes the use in industry and medicine of the named radioisotopes
Shows the link between the described properties of the radioisotopes and their
use in industry and medicine
6-7
Describes the benefits and problems of their use on society
Provides a judgement
Demonstrates coherence and logical progression and includes correct use of
scientific principles and ideas
Demonstrates a sound knowledge and understanding of named radioisotopes
Outline the use in industry and medicine of the named radioisotopes
Describes the properties of the radioisotopes
4-5
Outlines the benefits and problems of their use
Demonstrates an understanding of a named radioisotope
Identifies the use in industry or medicine of a named radioisotope
Outlines the property of the radioisotope
2-3
Outlines the benefit(s) and/or problem(s) of its use
Identifies a radioisotope used in medicine/industry
OR
Identifies a benefit or problem of the use of a radioisotope
1
OR
Identifies a property of a radioisotope
4
HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines
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Example Question 4: (2006 HSC Chemistry exam) Question 16 (3 marks)
Markers’ Comments:
This question was poorly answered by many candidates. A common misconception was that the
term ‘transuranic’ means ‘radioactive’.
Better responses defined the transuranic elements, identified the main features of two types of
technology and provided relevant examples.
Outcomes assessed: H1
Markers’ guidelines Question 16
Criteria
Marks
Describes how technology, including nuclear reactors and particle
accelerators have allowed for the production of transuranic elements
3
Outlines a method used to produce transuranic elements including the
name of a technology
2
• Identifies a transuranic element (by name or symbol)
OR
• Defines transuranic element
1
OR
• Identifies an example of a technology used to produce a transuranic
element
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HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines
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Example Question 5: (2004 HSC Chemistry exam) Question 26 (4 marks)
Markers’ Comments:
Candidates are reminded that they should be able to distinguish between industrial and
medical uses of radioisotopes. Better responses clearly identified a radioisotope used in
industry, including the correct mass number, and a well-structured answer that included
multiple points for and against an identified use of a radioisotope. Few responses showed a
clear link between the properties of the radioisotope and the benefits or problems
associated with these properties. It was evident that many candidates had little
understanding of industrial radioisotopes.
Outcomes assessed: H3, H4, H13
Markers’ guidelines Question 26
Criteria
Marks
Provides points for and/or against both the benefits and problems
associated with the use of a named radioisotope in industry
4
Describes a benefit and/or problem(s) associated with the use of a
named radioisotope in industry
2-3
OR
Describes benefits and problems in an industry for an incorrect
isotope of the element (for 2 marks maximum)
Identifies a benefit of a named radioisotope in industry/medicine
1
OR
Identifies a problem of a named radioisotope in industry/medicine
OR
Identifies a use of a named radioisotope in industry/medicine
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HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines
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Example Question 6: (2003 Paper) Question 18 (4 marks)
Markers’ Comments:
Better responses demonstrated a thorough knowledge of transuranic elements, commercial
radioisotopes, nuclear reactors, accelerators and the bombarding particles required in each
case.
Many candidates knew one specific radioisotope but few could define a transuranic
element.
Outcomes assessed: H3, H5, H8
Markers’ guidelines Question 18
Criteria
Marks
Demonstrates a thorough knowledge of methods of production of
both transuranic elements and commercial radioisotopes
4
Demonstrates a sound knowledge of methods of production of both
transuranic elements and commercial radioisotopes
2-3
• Identifies the location of the transuranic elements in the Periodic
Table
1
OR
• Identifies a transuranic element and/or commercial radioisotope
and its use
OR
• Identifies a method or piece of equipment used to produce
transuranic elements and/or commercial radioisotopes
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HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines
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Example Question 7: (2002 Paper) Question 19 (5 marks)
Markers’ Comments:
Most candidates indicated a reasonable understanding of nuclear chemistry. A significant
number of candidates wrote excessively long answers. Such long answers are likely to have
missed the point of the question or provide responses that contain contradictions.
(a) In this part most candidates wrote too much, going well beyond the allocated space.
Many candidates erroneously included electrons in their answer to a question on nuclear
stability.
(b) The majority of candidates interpreted the graph well.
Markers’ guidelines Question 19 a)
Criteria
Marks
Correctly identifies the features that make a nucleus unstable
2
Identifies that ‘protons’ and ‘neutrons’ are found in nucleus
1
OR
Correctly describes one condition under which a nucleus is unstable
Markers’ guidelines Question 19 b)
Criteria
Marks
Describes alpha and beta decay using examples from the flow
diagram
3
Describes alpha decay using an example from the flow diagram
2
OR
Describes beta decay using an example from the flow diagram
OR
Describes alpha and beta decay
Describes either alpha or beta decay
1
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HSC Chemistry 9.2.5 Production of Materials Example Questions – Marking Guidelines