A 5-gram sample of radioactive strontium-90 decayed over time. The graph shows the mass of strontium-90 remaining from the initial sample as a function of time.
What is the approximate value of the decay constant, in
- 0.006
- 0.011
- 0.014
- 0.025
Aussie Maths & Science Teachers: Save your time with SmarterEd
A 5-gram sample of radioactive strontium-90 decayed over time. The graph shows the mass of strontium-90 remaining from the initial sample as a function of time.
What is the approximate value of the decay constant, in
→ From the graph, the half life (mass = 2.5 g) is approximately 29 years.
Which of the following is true in relation to Millikan's oil drop experiment?
→ Millikan’s experiment involved levitating oil drops in an electric field in order to measure the charge on an electron.
After DC voltage was applied to an apparatus containing hydrogen gas, the hydrogen separated into streams of oppositely charged particles.
What could be concluded from this observation?
→ The separation shows that hydrogen atoms contain both positive (protons) and negative (electrons) components.
A Hertzsprung-Russell diagram is shown.
In which region would a star have the same surface temperature as a star on the main sequence?
→ Using the
A torque is applied to a nut, using a wrench.
Which change will increase the magnitude of applied torque?
→
→ Increasing the distance (
A sequence is given by the recursive formula
Using mathematical induction to show the formula for the general term of the sequence is
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Solve
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A researcher estimates the number of brumbies in a National Park after
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i.
ii.
iii.
iv.
The population of Myna birds in a national park is decreasing at a rate proportional to the population at that time.
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i.
ii. | ||
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i.
ii.
iii.
Use vector methods to find the coordinates of the point that divides the interval joining the points
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Two planes are flying in directions given by the vectors
A person in the flight control centre is plotting their paths on a map.
Calculate the acute angle between their projected flight paths, giving your answer correct to one decimal place. (2 marks)
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A parallelogram is formed by joining the points
Use vector methods to find
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In triangle
Use vector methods to prove that
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i.
ii.
Use vector methods to find the coordinates of the point that divides the interval joining the points
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Use two vector methods to locate the midpoint of the interval joining the points
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If
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i. | ||
ii.
In which of the following cases would bacteria be described as pathogens?
→ A pathogen is a biological agent of disease.
→ Bacteria ‘A’ is the only one which fits the criteria of a pathogen.
An object is projected upwards from the ground, and follows a path as represented in the diagram.
Which of the following describes the projectile's horizontal and vertical acceleration at point
→ There are no horizontal forces acting on the ball throughout its flight, so its horizontal acceleration is always zero.
→ The ball experiences a net downwards force due to gravity. This results in a constant vertical acceleration of
Some students were testing the hypothesis that launching a projectile at an angle of 45° will give the maximum horizontal range.
Which experimental setup will best test the hypothesis?
By Elimination:
→ In this experiment horizontal range is the dependent variable and launch angle is the independent variable. So, launch angle must be varied (eliminate
→ To be a valid experiment, the independent variable, i.e. the launch angle, must be the only variable which changes (eliminate
→ Between
The diagram shows an aerofoil.
Which condition needs to be achieved for lift to occur?
→ For a net upwards force, the force from pressure below (pushing up) must exceed the force from pressure above (pushing down).
→ Therefore Pressure 1<Pressure 2.
Which of the following is the circuit symbol for a diode?
The steel used in the chassis members was tested.
The load–extension graph represents the data collected during the testing of a specimen of the steel.
Before testing, the specimen was 1020 mm long with a cross-sectional area of 100 mm².
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i. Young’s modulus
ii. → Elastic deformation is produced by the 20 kN load.
→ After initial stretching the specimen returns to its original length.
→ Plastic deformation is produced by the 30 kN load.
→ The specimen stays deformed subsequent to release.
i. Young’s modulus
ii. → Elastic deformation is produced by the 20 kN load.
→ After initial stretching the specimen returns to its original length.
→ Plastic deformation is produced by the 30 kN load.
→ The specimen stays deformed subsequent to release.
Outline the benefits of using electric motors to power self-driving vehicles. (3 marks)
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Successful engines should include three of the following:
→ Reduced amount of tailpipe emissions through the use of renewable energy as the power source.
→ Lighter engine construction produces a better power to weight ratio.
→ Quieter engines reduce noise pollution.
→ Technology enabling simpler integration into an automated vehicle control system.
→ Less moving parts in electric motors mean they break down less often and need less maintenance.
Successful engines should include three of the following:
→ Reduced amount of tailpipe emissions through the use of renewable energy as the power source.
→ Lighter engine construction produces a better power to weight ratio.
→ Quieter engines reduce noise pollution.
→ Technology enabling simpler integration into an automated vehicle control system.
→ Less moving parts in electric motors mean they break down less often and need less maintenance.
Aircraft skins can be constructed using either fibre metal laminate (FML) or sheet aircraft-grade aluminium alloy.
FML is preferred in this application because it has
→ Higher density and lower Young’s modulus are both negative material properties for aircraft skins, as these skins should be light (lower density) and rigid (higher stiffness/Young’s modulus).
→ Additionally, fatigue resistance is important as aircraft skins are exposed to varying air pressures.
In which of the following do all of the processes require plastic deformation to achieve a final shape?
→ Brazing, casting, soldering and welding involve metal in liquid form and therefore do not require plastic deformation. (Cannot be
An arrangement of resistors is shown.
What is the total resistance of this arrangement of resistors?
Two types of bridge are shown.
What are the two types of bridge design shown?
→ Both bridges are arch beams, therefore C is correct.
→ In suspension bridges, the deck is suspended from above by vertical cables.
→ Beam bridges are a simple flat beam from one side to another, neither of which are shown here.
Digital logic controls a self-driving vehicle's brakes.
Brakes will be applied when all of the following conditions are met:
Explain how the logic gates, labelled 1, 2 and 3 in the circuit below, control the vehicle's brakes. (3 marks)
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A large epidemiological study was conducted. It used historical data to investigate the association between Herpes simplex virus (HSV) infection and dementia. Dementia is caused by a variety of brain illnesses. Alzheimer's disease is the most common cause of dementia.
The study used the records of 8362 patients with HSV infection and 25086 randomly selected sex- and age-matched control patients without HSV infection. Some of the patients with HSV had been treated with antiviral medication.
The graph below shows some results of the study.
→ The graph clearly shows that individuals with untreated HSV are at a greater risk of developing Alzheimer’s. While people without HSV or treated HSV remain relatively low up to 10 years, HSV patients can have 10 to 15 times the likelihood of developing Alzheimer’s, a trend which increases with age/time with HSV.
→ The treated HSV patients remain relatively low and almost identical to the individuals without HSV until 10 years where there is a sharp increase. However, it is still half the risk of untreated patients.
→ People without HSV have an incredibly low likelihood of obtaining Alzheimer’s, with only a very small increase in the 10 year follow up.
Data Trends:
→ The graph clearly shows that individuals with untreated HSV are at a greater risk of developing Alzheimer’s. While people without HSV or treated HSV remain relatively low up to 10 years, HSV patients can have 10 to 15 times the likelihood of developing Alzheimer’s, a trend which increases with age/time with HSV.
→ The treated HSV patients remain relatively low and almost identical to the individuals without HSV until 10 years where there is a sharp increase. However, it is still half the risk of untreated patients.
→ People without HSV have an incredibly low likelihood of obtaining Alzheimer’s, with only a very small increase in the 10 year follow up.
A telecommunications tower with repeater transmitters is shown. The tower is assembled from many individual parts.
Explain why detailed drawings are used in the design and manufacture of these individual parts. (2 marks)
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→ A scaled ‘Detail Drawing’ is required for a Structural Engineer to communicate information regarding individual parts.
→ To ensure accurate manufacture of parts that fit together during assembly, the detailed drawing would use a suitable scale so all details are apparent (eg 2:1, 5:1 and 10:1).
→ There is a high risk of inaccurately manufactured parts if detailed drawings are not provided.
→ A scaled ‘Detail Drawing’ is required for a Structural Engineer to communicate information regarding individual parts.
→ To ensure accurate manufacture of parts that fit together during assembly, the detailed drawing would use a suitable scale so all details are apparent (eg 2:1, 5:1 and 10:1).
→ There is a high risk of inaccurately manufactured parts if detailed drawings are not provided.
A telecommunications engineer has designed a tower that is to support two mobile repeater transmitters. It is to be located in an urban community.
Outline responsibilities the engineer has when placing the tower within a local community. (3 marks)
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Answers could include 3 of the following points:
→ Minimise health risks, so tower not erected near high density housing, childcare centres or schools.
→ Designed so visual pollution reduced.
→ Positioned so best possible signals are achieved and dead spots are minimised.
→ Easy accessibility for maintenance without consequences to the community.
→ Construction completed with least possible disruption to the community.
Answers could include 3 of the following points:
→ Minimise health risks, so tower not erected near high density housing, childcare centres or schools.
→ Designed so visual pollution reduced.
→ Positioned so best possible signals are achieved and dead spots are minimised.
→ Easy accessibility for maintenance without consequences to the community.
→ Construction completed with least possible disruption to the community.
The table shows materials that have been used to build civil structures over time.
Which row of the table shows the use of the materials in the correct historical order?
By Elimination:
→ Stainless steel must have been used after mild steel as it is an alloy of mild steel (not
→ Stone was used before iron as it did not require any processes to be formed (not
A box sits on a horizontal surface. The box begins to slip when this surface is tilted to 28 degrees.
What is the coefficient of friction between the box and the surface?
Which AND gate shows the correct output for its given inputs?
→ AND gates require 2 ‘high’ or ‘on’ inputs, in this case both inputs have to be 5V.
Which Australian aeronautical innovation is commonly used to record in-flight data?
→ A black box is the only option that records in flight data.
The position of the Sun, star
The curves
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i. → Curve A represents star
→
ii. Differences displayed in H-R graph:
→ Star
→ Star
→ Since star
Other possible answers could include:
→ Differences in fuel source, size and temperature of the stars.
i. → Curve A represents star
→
ii. Differences displayed in H-R graph:
→ Star
→ Star
→ Since star
Other possible answers could include:
→ Differences in fuel source, size and temperature of the stars.
Identify the TWO types of nucleon and state ONE difference between them. (2 marks)
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→ Nucleon types: Neutrons and protons.
→ Difference: Protons are positively charged whereas neutrons have no charge.
→ Nucleon types: Neutrons and protons.
→ Difference: Protons are positively charged whereas neutrons have no charge.
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i. Cornea and lens
ii. Differences in visual perception at
→ At the fovea (where
→ At the periphery (where
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a. Vasoconstriction and shivering.
b. Body temperature maintenance in endotherms:
→ This is achieved via negative feedback loops.
→ Temperature receptors in the brain and skin detect changes in body temperature.
→ The central nervous system receives a signal via the receptors.
→ Muscles or glands (effectors) then receive nerve signals sent from the central nervous system.
a. Vasoconstriction and shivering.
b. Body temperature maintenance in endotherms:
→ This is achieved via negative feedback loops.
→ Temperature receptors in the brain and skin detect changes in body temperature.
→ The central nervous system receives a signal via the receptors.
→ Muscles or glands (effectors) then receive nerve signals sent from the central nervous system.
A zebronkey hybrid is the result of crossing a male zebra which has 44 chromosomes with a female donkey which has 62 chromosomes.
How many chromosomes will the zebronkey have?
→ A haploid set of 22 chromosomes came from the zebra and 31 came from the donkey.
What is the probability of producing a tall pea plant when a heterozygous tall pea plant is crossed with a homozygous short pea plant?
→ Half the gametes produced by the heterozygous pea will have the T allele and the other half the t.
→ The homozygous short produces only t that are dominated by the T.
Which waste product does renal dialysis remove?
What name is given to the process whereby a white blood cell engulfs a microorganism?
→ Phagocytes are white blood cells in the body and they use phagocytosis to engulf microorganisms.
What is the role of lymphocytes in the body?
→ Lymphocytes (B and T cells) protect the body from pathogens by coordinating the immune response.
Which row of the table correctly matches the polymer with its structural feature and property?
→ A chlorine side group is responsible for the property of rigidity in polymers.
Students conducted preliminary experiments across different species to analyse their DNA base composition.
The table shows the experimental data collected.
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a.
b. As % Adenine increases, the % Guanine decreases.
c. Explanation of data relationship:
→ Adenine and Thymine are complementary base pairs. Likewise with Guanine and Cytosine.
→ It would therefore be expected that as the percentage of adenine increases, the percentage of thymine would also increase.
→ Adenine + Thymine + Cytosine + Guanine = 100%
→ It follows that as adenine increases the amount of guanine should decrease.
a.
b. As % Adenine increases, the % Guanine decreases.
c. Explanation of data relationship:
→ Adenine and Thymine are complementary base pairs. Likewise with Guanine and Cytosine.
→ It would therefore be expected that as the percentage of adenine increases, the percentage of thymine would also increase.
→ Adenine + Thymine + Cytosine + Guanine = 100%
→ It follows that as adenine increases the amount of guanine should decrease.
Name an infectious disease and explain how ONE host response is a defence adaptation. (3 marks)
Exemplar solution:
→ A primary immune response is triggered when a person first contracts chicken pox – an infectious disease.
→ Activated B and T cells reproduce in large numbers to fight and destroy the pathogen.
→ The host survives.
→ Subsequent infection with the same pathogen results in an increased secondary immune response.
Exemplar solution:
→ A primary immune response is triggered when a person first contracts chicken pox – an infectious disease.
→ Activated B and T cells reproduce in large numbers to fight and destroy the pathogen.
→ The host survives.
→ Subsequent infection with the same pathogen results in an increased secondary immune response.
Which row of the table correctly matches the reaction type with the reactant(s), catalyst and product(s)?
→ The dehydration of an alkanol
Which diagram represents ionisation of a weak acid?
→ Partial ionisation will result in a solution that contains hydronium, anions and water.
A camp stove using butane as a fuel was used to heat a pot of water inside a small tent. Poisonous carbon monoxide
An investigation was carried out to determine the carbon monoxide concentration in the tent when the clearance height of the pot above the flame was altered. The results are shown in the table.
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Ethylene can be readily transformed into many useful products.
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a. Cracking
b. Vinyl chloride:
Polyvinyl chloride:
a. Cracking
b. Vinyl chloride:
Polyvinyl chloride:
The following plants were presented to a quarantine office in Australia as part of a shipment of plants entering Australia for the plant nursery trade.
Which of the following is a decision that the quarantine office is likely to make?
→ The aim of quarantine is to prevent any pathogens from entering the country.
→ Any plant that appears to contain live insects has a chance of carrying international diseases, and will therefore be quarantined.
The image shows a laminated veneer lumber (LVL) beam that is used to span long distances in buildings.
Give reasons for using LVL instead of a steel beam as the supporting member in a building. (2 marks)
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Possible reasons include:
→ LVL has higher strength to weight ratio
→ Easier to attach to other timber framing members
→ Uses timber otherwise thrown away as waste
→ Can use defective timber as surrounding layers will support defects
→ Cheaper
→ Easier to colour
Possible reasons include:
→ LVL has higher strength to weight ratio
→ Easier to attach to other timber framing members
→ Uses timber otherwise thrown away as waste
→ Can use defective timber as surrounding layers will support defects
→ Cheaper
→ Easier to colour
A mixture of carbon monoxide, chlorine and phosgene
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a. At two minutes (where the concentrations stop changing)
b.
→ From the graph, when the temperature is increased, the
→ The reaction is countering the increase in temperature by shifting to the left and absorbing heat (Le Chatelier’s principle).
→ Therefore the decomposition of
a. At two minutes (where the concentrations stop changing)
b.
→ From the graph, when the temperature is increased, the
→ The reaction is countering the increase in temperature by shifting to the left and absorbing heat (Le Chatelier’s principle).
→ Therefore the decomposition of
This apparatus was set up to produce methyl butanoate.
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a. Flame could ignite one of reagents which is flammable.
b.
c. → Esterification is a relatively slow reaction.
→ Heating the reaction makes it go faster. However, the low boiling points of the reactants make them volatile as they readily convert into gas.
→ The cooling condenser
a. Flame could ignite one of reagents which is flammable.
b.
c. → Esterification is a relatively slow reaction.
→ Heating the reaction makes it go faster. However, the low boiling points of the reactants make them volatile as they readily convert into gas.
→ The cooling condenser
A polymer has the following structure.
Which of the following represents the monomer from which this polymer can be produced?
→ Break the polymer at every second
→ Adjust single carbon bond to
What is the name of this compound?
→ The compound is known as chloroethene or vinyl chloride.
It is appropriate to produce a half development of a transition piece when the piece
→ Half development of a transition piece is appropriate when it is symmetrical.
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a. Methodology:
→ Collect plant material that is a natural indicator of pH. Examples include rose petals and red cabbage.
→ Cut the coloured parts into small pieces.
→ Place material into a beaker with water and boil until the solution becomes coloured.
→ Allow the mixture to cool at room temperature.
→ Decant the liquid into a container, leaving the solid behind.
b. → Prepare test tubes of various acids and bases (pH of each is known).
→ Add some of the indicator to each test tube.
→ Record the natural indicator colour of each example and whether it differentiates between acids and bases and their concentrations.
a. Methodology:
→ Collect plant material that is a natural indicator of pH. Examples include rose petals and red cabbage.
→ Cut the coloured parts into small pieces.
→ Place material into a beaker with water and boil until the solution becomes coloured.
→ Allow the mixture to cool at room temperature.
→ Decant the liquid into a container, leaving the solid behind.
b. → Prepare test tubes of various acids and bases (pH of each is known).
→ Add some of the indicator to each test tube.
→ Record the natural indicator colour of each example and whether it differentiates between acids and bases and their concentrations.