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CHEMISTRY, M5 2021 HSC 22

Consider the following equilibrium system.

The solution is orange.

Justify TWO ways to shift the equilibrium to the left to change the colour of the solution.   (3 marks)

Show Answers Only

Answers could include two of the following methods.

Add ions:

→ This would increase the concentration of ions.

→ According to Le Chatelier’s Principle, this would cause the equilibrium to shift left to counteract the change and decrease the concentration of ions.
 

Decrease the concentration of ions by adding a base:

→ This would decrease the concentration of ions through an acid-base reaction.

→ According to Le Chatelier’s Principle, this would cause the equilibrium to shift left to counteract the change and increase the concentration of ions.
 

Increase the temperature:

→ According to Le Chatelier’s Principle, this would cause the equilibrium to shift left towards the endothermic side to counteract the change and decrease the temperature. 

Show Worked Solution

Answers could include two of the following methods.

Add ions:

→ This would increase the concentration of ions.

→ According to Le Chatelier’s Principle, this would cause the equilibrium to shift left to counteract the change and decrease the concentration of ions.

Decrease the concentration of ions by adding a base:

→ This would decrease the concentration of ions through an acid-base reaction.

→ According to Le Chatelier’s Principle, this would cause the equilibrium to shift left to counteract the change and increase the concentration of ions.

Increase the temperature:

→ According to Le Chatelier’s Principle, this would cause the equilibrium to shift left towards the endothermic side to counteract the change and decrease the temperature. 

CHEMISTRY, M8 2021 HSC 21

Four organic liquids are used in an experiment. The four liquids are

    • hexane
    • hex-1-ene
    • propan-1-ol
    • propanoic acid
  1. State ONE safety concern associated with organic liquids and suggest ONE way to address this safety concern.   (2 marks)

  2. The organic liquids are held separately in four flasks but the flasks are not labelled. Tests were conducted to identify these liquids. The outcomes of the tests are summarised below.   (2 marks)
     
           
    Identify the FOUR liquids.
     
           
  3. What chemical test, other than those used in part (b), could be used to confirm the identification of ONE of the liquids? Include the expected observation in your answer.   (2 marks)

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a.    A safety concern is that the organic liquids are flammable.

To address this, keep substance away from open flames and keep away from ignition sources.
 

b.    Flask 1: propanoic acid  (carboxylic acids can’t be oxidised and are polar)

Flask 2: hex-1-ene (alkenes can be oxidised and are non-polar)

Flask 3: propan-1-ol (primary alcohols can be oxidised and are polar)

Flask 4: hexane (alkanes don’t react with acidified oxidants and are non-polar)
 

c.   Hex-1-ene

→ Could be identified using the bromine water test.

→ The addition of brown bromine water to an alkene causes an addition reaction where the solution changes colours from brown to colourless.

Propanoic acid

→ Could be identified through a neutralisation reaction using .

→ Effervescent reaction will result.

Propan-1-ol

→ Could be identified through an oxidation reaction using acidified dichromate.

→ The reaction would cause the solution to change from green to orange.

Show Worked Solution

a.    A safety concern is that the organic liquids are flammable.

To address this, keep substance away from open flames and keep away from ignition sources.
 

b.    Flask 1: propanoic acid  (carboxylic acids can’t be oxidised and are polar)

Flask 2: hex-1-ene (alkenes can be oxidised and are non-polar)

Flask 3: propan-1-ol (primary alcohols can be oxidised and are polar)

Flask 4: hexane (alkanes don’t react with acidified oxidants and are non-polar)
 

c.   Hex-1-ene

→ Could be identified using the bromine water test.

→ The addition of brown bromine water to an alkene causes an addition reaction where the solution changes colours from brown to colourless.

Propanoic acid

→ Could be identified through a neutralisation reaction using .

→ Effervescent reaction will result.

Propan-1-ol

→ Could be identified through an oxidation reaction using acidified dichromate.

→ The reaction would cause the solution to change from green to orange.

ENGINEERING, AE 2021 HSC 23a

Due to a reduction in air travel, an airline company has had to store some of its unused aircraft.

Explain why the desert is a suitable place to store the unused aircraft.   (3 marks)

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→ Aircraft are susceptible to corrosion as they are constructed from aluminium. Specifically, crevice corrosion in the joints between the aluminium sheets.

→ While the aircraft are in storage they should be kept in a dry area to prevent any moisture from entering the crevices.

→ A desert provides this environment at a low cost.
 

Successful answers could also include:

→ Deserts also have fewer insects/wildlife which could nest in the aircraft.

→ The surface of the desert is also hard and dry so paving is not required.

Show Worked Solution

→ Aircraft are susceptible to corrosion as they are constructed from aluminium. Specifically, crevice corrosion in the joints between the aluminium sheets.

→ While the aircraft are in storage they should be kept in a dry area to prevent any moisture from entering the crevices.

→ A desert provides this environment at a low cost.
 

Successful answers could also include:

→ Deserts also have fewer insects/wildlife which could nest in the aircraft.

→ The surface of the desert is also hard and dry so paving is not required.

BIOLOGY, M6 2020 HSC 12 MC

What is the purpose of cloning in agriculture?

  1. Increasing the frequency of recessive traits
  2. Preserving favourable traits in the offspring
  3. Preserving genetic variability in a population
  4. Increasing combinations of alleles in a population
Show Answers Only

Show Worked Solution

→ Cloning is often used in agricultural practises within both flora and fauna to preserve favourable market characteristics, such as muscle size in cows.

BIOLOGY, M8 2020 HSC 1 MC

In maintaining homeostasis, which of the following is a behavioural adaptation?

  1. Sweating to cool down
  2. Curling up in a ball to keep warm
  3. Speeding up or slowing down cell metabolism
  4. Skin going red as more blood flows to surface
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Show Worked Solution

Curling into a ball to keep warm is a behavioural response of an organism that helps it maintain body temperature.

BIOLOGY, M7 2021 HSC 16 MC

Scientists conducted an experiment to investigate the effectiveness of treating water from storage dams with UV radiation.

The experiment was conducted more than three times. The results are shown in the table.
 

What conclusion may be drawn from the data obtained?

  1. The control plates are contaminated.
  2. High doses of UV eliminate all pathogens.
  3. Exposure to UV inhibits reproduction of bacteria.
  4. The presence of bacteria reduces the amount of UV.
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Show Worked Solution

→ As the UV dose increased, the number of bacteria decreased.

♦ Mean mark 79%.

PHYSICS, M7 2017 HSC 21

A laser emits light of wavelength 550 nm.

  1. Calculate the frequency of this light.   (2 marks)
  1. The electrons in a specific metal must absorb a minimum of    in order to be ejected from its surface.
  2. Explain why electrons will not be ejected from this metal when photons of wavelength 550 nm strike its surface. Support your answer with relevant calculations.   (3 marks)

 

Show Answers Only

a.   

b.   
   

Show Worked Solution
a.
 
   
   

 

b.
   
   

 
→ The work function of the metal sample is  .

→ Since the incident photon energy of    is less than  , they are unable to eject electrons from the metal.

PHYSICS M5 2022 HSC 25

A rocket is launched vertically from a planet of mass . After it leaves the atmosphere, the rocket's engine is turned off and it continues to move away from the planet. From this time the rocket's mass is 200 kg. The rocket's speed, , at two different distances from the planet's centre, , is shown.

  1. Show that the magnitude of the change in kinetic energy from point 1 to point 2 is  .  (2 marks)

  1. Determine the mass of the planet using the law of conservation of energy.  (3 marks)

Show Answers Only

a. 

 
 
 
 

 

 
   

This change has a magnitude of .
 

b.   Applying the law of conservation of energy:

→ The magnitude of kinetic energy lost is equal to the magnitude of potential energy gained by the rocket:

 
   

 

 


 

 
   
Show Worked Solution

a. 

 
 
 
 

 

 
   

This change has a magnitude of . 

b.   Applying the law of conservation of energy:

→ The magnitude of kinetic energy lost is equal to the magnitude of potential energy gained by the rocket:

 
   

 

 


 

 
 

♦ Mean mark 47%.

PHYSICS M8 2022 HSC 24

The radioactive decay curve for americium-242 is shown.
 


 

  1. Use the graph to find the half-life of Am-242 and hence show that the decay constant, , is   (2 marks)
  1. Calculate how long it takes until the mass of Am-242 is 8 micrograms.  (2 marks)
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a.   

b. 

Show Worked Solution

a.   The half life of Am-242 is 16 hours.

 
   
   

 

b.    
     
 
 
     
   

PHYSICS M8 2022 HSC 21

The positions of two stars, and , are shown in the Hertzsprung-Russell diagram.
 

  1. Compare qualitatively the surface temperature and luminosity of and .  (2 marks)

  1. Identify the elements undergoing fusion in the core of each star, and .  (2 marks)
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a.   Surface Temperature: The surface temperature of is greater than the surface temperature of

Luminosity: The luminosity of is greater than the luminosity of
 

b.   → is a main sequence star so in its core hydrogen is being fused into helium.

→ is a red giant so in its core helium is being fused into carbon.

Show Worked Solution

a.   Surface Temperature:

→ The surface temperature of is greater than the surface temperature of

Luminosity:

→ The luminosity of is greater than the luminosity of
 

b.    → is a main sequence star so in its core hydrogen is being fused into helium.

→ is a red giant so in its core helium is being fused into carbon.

BIOLOGY, M8 2021 HSC 25

A patient visited an audiologist for a hearing test. The audiologist tested both ears at specific frequencies. The volumes at which each frequency could be heard are shown.
 

  1. Plot the data on the grid provided and include a key.   (3 marks)
     

  1. What conclusions can be drawn about the patient's hearing?   (2 marks)

  2. It is discovered that there is a complete and permanent blockage of the outer ear, but the cochlea is still fully functional.
  3. Justify the use of a suitable technology to assist the patient's hearing.   (3 marks)

Show Answers Only

a.  


 

b.   Right ear is within normal hearing range.

Left ear has a deficit and cannot hear at a normal level.
 

c.    Effective technology: Bone Conduction Implants

Bone conduction implants would prove to be the most effective technology to restore hearing to this patient. 

Bone conduction implants detect sound waves via a microphone, relaying them to a sound processor that converts the waves into vibrations which are then directly transferred to the cochlea. This process bypasses the ear blockage, therefore restoring hearing to the patient.

Show Worked Solution

a.   


 

b.   → Right ear is within normal hearing range.

→ Left ear has a deficit and cannot hear at a normal level.
 

c.    Effective technology: Bone Conduction Implants

→ Bone conduction implants would prove to be the most effective technology to restore hearing to this patient. 

→ Bone conduction implants detect sound waves via a microphone, relaying them to a sound processor that converts the waves into vibrations which are then directly transferred to the cochlea.

→ This process bypasses the ear blockage, therefore restoring hearing to the patient.


♦ Mean mark (c) 43%.

BIOLOGY, M5 2021 HSC 23

Ovulation in women is associated with a rapid increase in luteinising hormone (LH). Test strips can be used to detect high levels of LH in urine. Once a test strip is used, a control line should appear and the presence of a test line indicates high levels of LH in urine. The image below represents four different results that were obtained.
 

Which of the results indicates a valid test which shows that ovulation is NOT occurring? Justify your answer.   (3 marks)

Show Answers Only

→ Test strips 3 and 4 do not contain a control line, therefore are invalid.

→ Test strip 2 contains a control line but no test line, indicating that there was no LH surge.

→ Therefore, test strip 2 indicates a valid negative result that shows ovulation is not occurring.

Show Worked Solution

→ Test strips 3 and 4 do not contain a control line, therefore are invalid.

→ Test strip 2 contains a control line but no test line, indicating that there was no LH surge.

→ Therefore, test strip 2 indicates a valid negative result that shows ovulation is not occurring.

PHYSICS M5 2022 HSC 8 MC

An object is launched with an initial velocity, , and hits a wall with a final velocity, .
 


 

Which statement correctly compares components of and ?

  1. The vertical component of is less than the vertical component of .
  2. The vertical component of is greater than the vertical component of .
  3. The horizontal component of is less than the horizontal component of .
  4. The horizontal component of is greater than the horizontal component of .
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Show Worked Solution

The vertical velocity of the projectile decreases under the influence of gravity. The horizontal velocity of the projectile remains constant.

PHYSICS M8 2022 HSC 5 MC

Protons and neutrons are made up of quarks. The table shows the charges of these quarks.
 


 

What combination of quarks forms a neutron?

  1. 1 up, 1 down
  2. 1 up, 2 down
  3. 2 up, 1 down
  4. 2 up, 2 down
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Show Worked Solution

Baryons such as neutrons are always are made up of three quarks.

Neutrons are electrically neutral

→ comprised of one up quark and two down quarks.

PHYSICS M6 2022 HSC 3 MC

A radioisotope emits radiation which is deflected by an electric field, as shown.
 


 

What type of radiation is this?

  1. Alpha
  2. Gamma
  3. Beta positive (positron)
  4. Beta negative (electron)
Show Answers Only

Show Worked Solution

The radiation experiences a force of attraction towards the positive plate.

→ it must be negatively charged.

PHYSICS M8 2022 HSC 2 MC

The absorption lines in a star's spectrum are shown.
 

What feature of the star is directly responsible for these absorption lines?

  1. Size
  2. Colour
  3. Distance from Earth
  4. Chemical composition
Show Answers Only

Show Worked Solution

Elements and compounds in the stars’ atmosphere will absorb specific wavelengths of light which correspond to these absorption lines.

→ chemical composition is responsible.

BIOLOGY, M7 2021 HSC 21

  1. Label TWO features on the diagram below that would help to classify this pathogen as a bacterium.   (2 marks)
     
     

     
  2. A scientist followed Koch's postulates to confirm that this bacterium was causing diarrhoea in pigs on a local farm. 
  3. Complete the boxes in the flowchart provided to show the steps taken by the scientist.    (2 marks)
     
     

  4.  
  5. Two pig farmers on neighbouring farms noticed that their pigs were suffering from diarrhoea and gradually losing weight. The farmers each adopted a different strategy to deal with this disease, as shown in the table.  

Outline ONE benefit and ONE limitation of the strategies used on each farm.   (3 marks)

Show Answers Only

a.    Include two of the following labels:
 
       

b.   Box 2: Bacteria grown in pure culture and identified.

Box 4: Healthy pig became ill with diarrhoea.
 

c.   Benefits and Limitations of the strategies used on each farm.

→ The use of antibiotics on farm 1 has resulted in a rapid elimination of diarrhoea cases, however may induce antibiotic resistance in the
future, rendering the strategy less effective.

→ The removal of rats and mice from pig sheds to increase hygiene on farm 2 is slow to eliminate diarrhoea cases, however provides reassurance to prevent future outbreaks.
 

Other correct answers:

→ Proper hygiene practices can reduce incidence of other diseases, not just diarrhoea.

Show Worked Solution

a.    Include two of the following labels:
 
       
 

b.   Box 2: Bacteria grown in pure culture and identified.

Box 4: Healthy pig became ill with diarrhoea.
 

c.   Benefits and Limitations of the strategies used on each farm.

The use of antibiotics on farm 1 has resulted in a rapid elimination of diarrhoea cases, however may induce antibiotic resistance in the
future, rendering the strategy less effective.

The removal of rats and mice from pig sheds to increase hygiene on farm 2 is slow to eliminate diarrhoea cases, however provides reassurance to prevent future outbreaks.
 

Other correct answers:

  • Proper hygiene practices can reduce incidence of other diseases, not just diarrhoea.

Calculus, EXT1 C1 2022 HSC 12d

In a room with temperature 12°C, coffee is poured into a cup. The temperature of the coffee when it is poured into the cup is 92°C, and it is far too hot to drink.

The temperature, , in degrees Celsius, of the coffee, minutes after it is made, can be modelled using the differential equation  , where is the constant of proportionality and is a constant.

  1. It takes 5 minutes for the coffee to cool to a temperature of 76°C.
  2. Using separation of variables, solve the given differential equation to show that  .  (3 marks)

  3. The optimal drinking temperature for a hot beverage is 57°C.
  4. Find the value of when the coffee reaches this temperature, giving your answer to the nearest minute.  (1 mark)

Show Answers Only
Show Worked Solution

i.   

 
 
 
 

 

 
 

 

 
 
 
 

 

 
 
 
 

  

 

ii.   

 
 
 
 
   
   

Calculus, 2ADV C3 2022 HSC 27

Let  .

It is given that  .

  1. Show that  .  (2 marks)

  2. Find any stationary points of    and determine their nature.  (2 marks)

  3. Sketch the curve  , showing any stationary points, points of inflection and intercepts with the axes.  (3 marks)

Show Answers Only
  3.  
Show Worked Solution

a.   

 
   
   
   

 

b.   

 
 

 

 
   

 

 

c.   


 


Mean mark part (c) 54%.

Calculus, 2ADV C3 2022 HSC 20

A scientist is studying the growth of bacteria. The scientist models the number of bacteria, , by the equation

,

where is the number of hours after starting the experiment.

  1. What is the initial number of bacteria in the experiment?  (1 mark)

  2. What is the number of bacteria 24 hours after starting the experiment?  (1 mark)

  3. What is the rate of increase in the number of bacteria 24 hours after starting the experiment?  (2 marks)

Show Answers Only
Show Worked Solution
a.   
   

 

b.   

 
   
   

 

c.   
 
   

 

 
   
   

Financial Maths, 2ADV M1 2022 HSC 17

Cards are stacked to build a 'house of cards'. A house of cards with 3 rows is shown.

A house of cards requires 3 cards in the top row, 6 cards in the next row, and each successive row has 3 more cards than the previous row.

  1. Show that a house of cards with 12 rows has a total of 234 cards.  (2 marks)

  2. Another house of cards has a total of 828 cards.
  3. How many rows are in this house of cards?  (3 marks)

Show Answers Only
Show Worked Solution

a.   

 
 
   
   

 
b.   

 
 
   

 

 
 
 

 

Statistics, 2ADV S2 2022 HSC 11

The table shows the types of customer complaints received by an online business in a month.

  1. What are the values of and ?  (2 marks)

  2. The data from the table are shown in the following Pareto chart.
     
     
  3. The manager will address 80% of the complaints.
  4. Which types of complaints will the manager address?  (1 mark)

Show Answers Only
Show Worked Solution

a.   


 

b.   

Statistics, STD2 S4 2022 HSC 23

A teacher surveyed the students in her Year 8 class to investigate the relationship between the average number of hours of phone use per day and the average number of hours of sleep per day.

The results are shown on the scatterplot below.
 

  1. The data for two new students, Alinta and Birrani, are shown in the table below. Plot their results on the scatterplot.  (2 marks)

                               
  2. By first fitting the line of best fit by eye on the scatterplot, estimate the average number of hours of sleep per day for a student who uses the phone for an average of 2 hours per day.  (2 marks)

Show Answers Only
Show Worked Solution

a.   

b.   

Financial Maths, STD2 F4 2022 HSC 27

A company purchases a machine for $50 000. The two methods of depreciation being considered are the declining-balance method and the straight-line method.

  1. For the declining-balance method, the salvage value of the machine after years is given by the formula
  2.    
  3. where is the salvage value and is the initial value of the asset.
  4.  i. What is the annual rate of depreciation used in this formula?  (1 mark)
  5. ii. Calculate the salvage value of the machine after 3 years, based on the given formula.  (1 mark)
  6. For the straight-line method, the value of the machine is depreciated at a rate of 12.2% of the purchase price each year.
  7. When will the value of the machine, using this method, be equal to the salvage value found in part (a) (ii)?  (2 marks)
Show Answers Only
  1.  i.
  2. ii.
Show Worked Solution

a.i. 
 

a.ii. 

 
   
   

 
b.   

 
   

 

 
 
 
   

♦♦ Mean mark (a.i.) 24%.
COMMENT: A poor State result in part (a.i.) that warrants attention.
 
♦ Mean mark part (b) 38%.

Networks, STD2 N2 2022 HSC 20

The table below shows the distances, in kilometres, between a number of towns.
 

  1. Using the vertices given, draw a weighted network diagram to represent the information shown in the table.  (2 marks)
     

     
  2. A tourist wishes to visit each town.
  3. Draw the minimum spanning tree which will allow for this AND determine its length.  (3 marks)
     

Show Answers Only
  1.  
     
     
  2.   
     
Show Worked Solution

a. 

 

b.   

Algebra, STD2 A2 2022 HSC 16

Tom is 25 years old, and likes to keep fit by exercising.

  1. Use this formula to find his maximum heart rate (bpm).
  2.      Maximum heart rate = 220 – age in years
  3. Tom's maximum heart rate is ........................... bpm.   (1 mark)
  4. Tom will get the most benefit from this exercise if his heart rate is between 50% and 85% of his maximum heart rate.
  5. Between what two heart rates should Tom be aiming for to get the most benefit from his exercise?  (2 marks)

Show Answers Only
Show Worked Solution
a.   
   

 

b.   

PHYSICS, M6 2019 HSC 24

A step-up transformer is constructed using a solid iron core. The coils are made using copper wires of different thicknesses as shown.
 

The table shows electrical data for this transformer.
 

  1. Explain how the operation of this transformer remains consistent with the law of conservation of energy. Include a relevant calculation in your answer.   (3 marks)
  1. Explain how TWO modifications to this transformer would improve its efficiency.   (4 marks)
Show Answers Only

a.    The energy input into this transformer is 500 J

The energy output is given by:

 
   
  J  

 
This is consistent with the law of conservation of energy as 500 J of energy is converted into other energy forms such as heat.
   

b.    → Laminating the iron core prevents large eddy currents from being induced in it.

→ This reduces energy loss in the form of heat, increasing efficiency.

→ Increasing the thickness of the wire in the primary coil reduces its resistance, increasing the transformer’s efficiency.

Show Worked Solution

a.   The energy input into this transformer is  500  J

The energy output is given by:

 
   
  J  

 
This is consistent with the law of conservation of energy as 500 J of energy is converted into other energy forms such as heat.
   

b.     Modification 1:

→ Laminating the iron core prevents large eddy currents from being induced in it.

→ This reduces energy loss in the form of heat, increasing efficiency.

Modification 2:

→ Increasing the thickness of the wire in the primary coil.

→ This reduces its resistance, increasing the transformer’s efficiency.


♦ Mean mark part 48%.

PHYSICS, M7 2019 HSC 2 MC

Two stars were observed from Earth. Their spectra are shown with the wavelength in nanometres.
 

Using these spectra, what can be concluded about the motion of the stars relative to Earth and their chemical compositions?
 

Show Answers Only

Show Worked Solution

Both stars have the same set of spectral lines → Chemical composition is the same.

Spectral lines at different wavelengths → Different doppler shift → Different motion relative to the earth.

PHYSICS, M7 2020 HSC 30b

  1. Calculate the wavelength of a proton travelling at 0.1.   (2 marks)
  1. Explain the relativistic effect on the wavelength of a proton travelling at 0.95.   (2 marks)
Show Answers Only

i.   m

ii.  See Worked Solutions

Show Worked Solution
i.     
   
   

   

ii.    Due to momentum dilation:

→ The momentum of the proton is greater than that predicted by classical mechanics. 

→ Since 

→ The wavelength of the proton is shorter than would be predicted by classical mechanics.


♦ Mean mark (ii) 45%.

PHYSICS, M6 2020 HSC 23

The graph shows data for a motor connected to a 240 V power supply.
 

The equation for the torque, , produced by the motor is 

where    torque (N m)
    voltage (V)
  current (A)
  efficiency 0.3
  angular velocity (rad )

 
A circuit breaker cuts the current to the motor if the current exceeds 5  A.

Determine what will happen when the motor produces a torque of 2.95 N m. Show relevant calculations.   (3 marks)

Show Answers Only

= 4.1 A

Current is below 5 A, so the circuit breaker will not cut the current and the motor will continue to run.

Show Worked Solution

From the graph, when 2.95,

 
 
   
  A  

 Current is below 5 A, so the circuit breaker will not cut the current and the motor will continue to run.

PHYSICS, M7 2020 HSC 3 MC

What was the basis for Maxwell's prediction of the velocity of electromagnetic waves?

  1. Experiments using magnetic fields to accelerate particles
  2. Experiments using light and mirrors to establish the finite speed of light
  3. Equations showing how oscillating electric and magnetic fields propagate
  4. Equations showing how electromagnetic waves are affected by gravitational fields
Show Answers Only

Show Worked Solution

Maxwell used equations to show interactions between electric and magnetic fields.

CHEMISTRY, M7 2021 HSC 4 MC

The structure of ethyl pentanoate is shown.
 

Which pair of chemicals would produce ethyl pentanoate by esterification?

  1. Ethene and pentan-1-ol
  2. Ethane and pentanoic acid
  3. Ethanol and pentanoic acid
  4. Ethanoic acid and pentan-1-ol
Show Answers Only

Show Worked Solution

→ Esterification involves a reaction between a carboxylic aciand an alcohol.

→ Creating ethyl pentanoate requires ethanol (which is an alcohol) and pentanoic acid (which is a carboxylic acid).

→ Ethanol + pentanoic acid  ↔ ethyl pentanoate + water