sci 3/4u core - board of studies

DIRECTIONS TO CANDIDATES

• Attempt ALL questions.

• Section I 10 multiple-choice questions, each worth 1 mark.Mark your answers in pencil on the Answer Sheet provided.

• Section II 10 questions, each worth 3 marks.Answer this Section in the Section II Answer Book.

• Section III 8 questions, each worth 5 marks.Answer this Section in the Section III Answer Book.

• Section IV 2 questions, each worth 10 marks.Answer this Section in the Section IV Answer Book.

• You may keep this Question Book. Anything written in the Question Book will NOT bemarked.

• A Data Sheet and Periodic Table are provided as a tear-out sheet at the back of this paper.

• Board-approved calculators may be used.

N E W S O U T H W A L E S

HIGHER SCHOOL CERTIFICATE EXAMINATION

1997

SCIENCE3/4 UNIT

PAPER 1—CORE

Time allowed—Three hours(Plus 5 minutes reading time)

2

SECTION I

Attempt ALL questions.

Questions 1–10 are worth 1 mark each.

Mark your answers in pencil on the Answer Sheet provided.

Select the alternative A, B, C, or D that best answers the question.

1 . Phosphoric acid, H3PO4, can be formed from solid phosphorus, P4, according to theoverall equation

P4(s) + 5O2(g) + 6H2O(l) → 4H3PO4(l).

The mass of H3PO4 that could be produced from 124 g of P4 is

(A) 98 g.

(B) 124 g.

(C) 392 g.

(D) 496 g.

2 . In an industrial process, coke is used as a source of carbon for extracting metals fromtheir ores. Which of the following metals could NOT be extracted from its main ore byusing coke?

(A) Aluminium

(B) Copper

(C) Iron

(D) Mercury

3 . Which of the following substances in the liquid state has polar molecules and a significantdegree of intermolecular hydrogen bonding?

(A) Hydrogen

(B) Methane

(C) Methanol

(D) Sodium chloride

3

4 . A farmer determined the pH of four soil samples. Which of the samples is likely tocontain the lowest concentration of hydrogen ions?

Soil sample pH

(A) A 5·6

(B) B 6·0

(C) C 7·6

(D) D 8·0

5 . A 2·0 kg mass is moving at 2·0 m s–1 on a horizontal frictionless surface. It collideselastically with a stationary 8·0 kg mass which is fitted with a spring of negligible mass.The spring is compressed in the collision. At the point of maximum compression, bothmasses have the same velocity.

2·0 kg

2·0 m s–1

8·0 kg

The momentum of the system of masses plus spring at maximum compression, is

(A) 0 kg m s–1.

(B) 2·0 kg m s–1.

(C) 4·0 kg m s–1.

(D) 8·0 kg m s–1.

6 . Assuming there is no friction, the greatest amount of work done on a 0·6 kg mass iswhen it is

(A) raised through a height of 11 metres.

(B) accelerated from rest to a speed of 15 m s–1.

(C) moved horizontally over a distance of 500 metres.

(D) taken over a 200 metres high hill and returned to its starting point.

4

7 . The schematic diagram below shows the arrangement of uniform resistance wires insidean electric blanket.

1

2

3

KEY

Resistance wire

Connecting wire ofnegligible resistance

Which terminals must be connected to a power supply in order to produce the greatestheating effect by the blanket?

(A) 1 only

(B) 1 and 2

(C) 1 and 3

(D) 2 and 3

8 . The cell structures directly involved in protein synthesis include

(A) endoplasmic reticulum, nucleus, ribosomes.

(B) chloroplasts, nucleus, endoplasmic reticulum.

(C) mitochondria, nucleus, vacuoles.

(D) vacuoles, chloroplasts, ribosomes.

5

9 . The diagram shows an animal cell.

This cell is undergoing

(A) cytokinesis.

(B) glycolysis.

(C) meiosis.

(D) mitosis.

1 0 . Of the following, the earliest lifeforms on Earth were

(A) armour-plated fish.

(B) filamentous bacteria.

(C) giant jellyfish.

(D) unicellular algae.

6

SECTION II


Questions 11–20 are worth 3 marks each.

Answer this Section in the Section II Answer Book.

Show all necessary working in questions involving calculations.

Marks may be awarded for relevant working.

1 1 . An organic substance consisting of carbon, hydrogen, and oxygen, was exploded with12·672 g of oxygen. The products were 15·488 g of carbon dioxide and 7·9200 g ofwater. The molar mass of the organic substance was 488·00 g mol–1.

(a) Calculate the empirical formula for the organic substance.

(b) What is the molecular formula of the organic substance?

12 . A group of students is required to do a titration. Initially they are asked to dilute 60·0 mLof a 3·000 mol L–1 sodium hydrogen carbonate stock solution to 0·1000 mol L–1. Thenthey titrate a 25·0 mL aliquot of this diluted solution against a 0·0750 mol L–1 sodiumhydroxide solution.

(a) Write a balanced equation to represent this reaction.

(b) What volume of water is required to dilute the stock solution of sodium hydrogencarbonate to 0·1000 mol L–1?

(c) Calculate the volume of sodium hydroxide solution required to neutralise the25·0 mL aliquot of sodium hydrogen carbonate.

13 . The formulae of three biochemical molecules are as follows:

X

(C6H11O5)O(C6H11O5)

Y

HOOCCH2CH2NH2

Z

CH2OOC(CH2)16CH3

CHOOC(CH2)16CH3

CH2OOC(CH2)16CH3

Complete the table in the Section II Answer Book.

7

14 . The mass of 0·5000 L of an unknown gas at 298 K and 101·3 kPa is 1·309 g. Theunknown gas is one of the following: SO2, CO2, P2O5, or NO2.

(a) (i) Calculate the molecular mass in grams of the unknown gas.

(ii) Name the gas.

(b) The gas is bubbled into water.

(i) Write the equation for the reaction that occurs.

(ii) Is the solution that is produced acidic or basic? Explain your answer.

1 5 . An electric train leaves Springwood (altitude 371 m) at 6.00 a.m. and completes the31·0 km journey to Katoomba (altitude 1017 m) at 6.30 a.m. A railway car has a massof 2·00 × 104 kg. For this railway car, calculate:

(a) the gain in gravitational potential energy;

(b) the average power required by the electric motors.

1 6 . (a) You are provided with three 12 ohm resistors. Draw a circuit diagram to show howthey could be connected to produce an effective total resistance of 18 ohms.

(b) Three resistors were set up in a circuit as shown.

A2

9 V

12 Ω

12 Ω

A1

R

KEY

A1 = 0·75 AA2 = 4·5 A

Calculate the resistance of the unknown resistor, R.

8

1 7 . Student X was riding a skateboard that had some ticker tape connected to it. The tickertimer had a frequency of 50 Hz. Student X collided with student Y who was stationaryon another skateboard. After the collision, the two skateboarders moved together in thesame direction.

Tape

Combined mass = 55 kg Combined mass = 68 kg

Student X Student Y

A section of the ticker timer record, drawn to scale, before the collision is shown.

(a) Calculate the speed of:

(i) student X before the collision;

(ii) students X and Y immediately after the collision.

(b) Is this collision elastic or inelastic? Use calculations to support your answer.

9

1 8 . The schematic diagram shows part of a DNA molecule.

(a) State which feature of this molecule enables it to function as a store of geneticinformation.

(b) Describe TWO features of the molecule that allow it to transmit exactly the sameinformation to two daughter cells resulting from mitosis.

10

1 9 . The map below illustrates the striped pattern of magnetic anomalies preserved in the seafloor off the west coast of North America.

(a) Describe how sea-floor rocks become magnetised.

(b) Describe what such striped patterns indicate about:

(i) Earth’s magnetic field over time;

(ii) the age of the ocean floors.

11

2 0 . (a) Multicellular plants and multicellular animals possess differentiated cells withspecial features. These features are directly related to the function of the cell.

(i) Name TWO differentiated cell types from multicellular plants or multicellularanimals.

(ii) List the function of each cell type.

(iii) List a specialised feature of each cell type.

(b) Name the tissue involved in photosynthesis in the leaf of a flowering plant.

(c) In plants, growth may vary with the seasons. Explain why cell growth often occursmore rapidly at warmer times of the year.

12

SECTION III



Answer this Section in the Section III Answer Book.



2 1 . Some properties of four substances are shown in the table.

Substance m.p. b.p. Electrical conductivity

(°C) (°C)solid liquid

aqueoussolution

A 113 445 low low —

B 1455 2730 high high —

C 801 1465 low high yes

D –114 –85 low low yes

(a) Describe the structure and bonding for substances A , B , and C . Use theinformation from the table to support your answer.

(b) Explain why substance D conducts electricity only in aqueous solution, and not inthe solid or liquid state.

2 2 . There are many oxidation–reduction reactions where one species acts as the oxidant andanother as the reductant.

(a) Define the term reductant.

(b) (i) Using the list of Standard Potentials on the Data Sheet, write the formula of:

1. a substance that can readily act as a reductant;

2. another substance that will react with the reductant you have chosen.

(ii) Write the overall equation to represent this reaction.

(c) Which substance from the list of Standard Potentials would most readily bereduced? Explain your answer.

(d) Briefly explain why potassium is not found in its elemental form in nature.

13

2 3 . A chemical substance with molecular formula C6H12 can be a member of two differenthomologous series.

(a) Define the term homologous series.

(b) Complete the table in the Section III Answer Book.

2 4 . A toaster was tested in a laboratory. Its voltage and current were measured and recordedas shown in the table.

Voltage(V)

Current(A)

50 1·0

100 1·9

150 3·2

200 4·0

(a) Draw a labelled graph showing the relationship between voltage and current.

(b) Using the graph drawn in part (a), calculate the resistance of the toaster.

(c) Calculate the power output of the toaster when it is connected to a 240 V supply.

(d) The toaster is left on for two minutes at 240 V. Calculate the amount of charge thatflows during this time.

14

25 . An object of mass 0·100 kg is travelling 10·0 m s–1 north, when it strikes a wall at P. Itthen strikes the wall at Q, rebounds, and returns along its original path. Its speed remainsat 10·0 m s–1 after each collision.

PQ

N

(a) Calculate the change in momentum of the object after its collision at Q.

(b) Calculate the overall change in momentum of the object as a result of the threecollisions.

(c) Calculate the total amount of work done by the wall in the three collisions. Explainyour answer.

(d) Explain how the collision of the object on the wall at Q obeys Newton’s Third Law.

2 6 . (a) Define the term index fossil.

(b) (i) Give TWO reasons why the fossil record does NOT contain examples of allorganisms that have lived.

(ii) Explain the impact of this with regard to evolutionary theory.

(c) Describe the evidence that indicates when life first appeared on Earth.

15

27 . Reconstructions from a set of hypothetical fossils are shown.

(a) Describe THREE apparent changes in these animals over time.

(b) Use the principle of natural selection to explain how ONE of these changes mayhave occurred.

(c) Describe how this sequence of fossils and sedimentary rock strata could be used toestablish a timescale over a large region.

16

28 . The following map of the Pacific Ocean floor reveals three principal topographic features:elongated mountain ranges (P), deep ocean trenches (Q), and broad flat abyssal plains(R).

Q

R

P

(a) What is the name given to the elongated mountain ranges (P)?

(b) Explain the origin of each of the topographic features (P, Q, and R) with referenceto the Plate Tectonic Theory. Use simple sketches to illustrate your answer.

(c) Describe the nature of earthquakes and volcanoes that are associated with theformation of the deep ocean trenches (Q).

17

SECTION IV



Answer this Section in the Section IV Answer Book.



2 9 . (a) A science teacher was performing experiments to measure respiration rates ofmitochondria. Varying amounts of mitochondria were added to a medium and theoxygen consumption was recorded during the experiment.

OXYGEN CONSUMPTION (µL) OF DIFFERENTAMOUNTS (mg) OF MITOCHONDRIA

0·75 mg0·50 mg

0·25 mg

KEY

Amounts of mitochondria

Oxy

gen

cons

umpt

ion

0

10

20

30

0 10 20Time (minutes)

L)µ(

(i) For a fixed amount of mitochondria, is the rate of oxygen consumptionconstant over the test period? Using the graph, justify your answer.

(ii) Describe the relationship between the amount of mitochondria and rate ofoxygen consumption.

(iii) Identify TWO factors that would need to be controlled in this experiment.

(iv) State ONE alternative to oxygen consumption that could be used as ameasure of respiration rate.

18

29. (Continued)

(b) A student investigated the physical properties of skeletal muscle from a cane toad.The student isolated a muscle and stimulated it electrically. The student was awarethat isolated muscles display the same biochemical processes as muscles in livingorganisms. The stimulated muscle contracted and lifted a mass of 1·50 kg througha height of 5·00 mm in 370 ms.

(i) For this muscle, calculate the:

1. average force applied;

2. work done;

3. power output.

(ii) When this muscle was connected to a smaller mass, the rate of contractionincreased. Explain why this occurred.

(iii) When the experiment was repeated regularly, the performance of the muscledecreased. Explain why this occurred.

19

3 0 . The map below shows an area that is rich in ores containing iron, formed fromhydrothermal processes. The primary iron ore minerals are contained in quartz veins.Pyrite (FeS2) is one of the primary ore minerals.

Rainwater washing over the quartz veins has leached the primary ore minerals. Ironcompounds have precipitated, forming sediments in rivers draining from this area. Theiron concentration in the river sediments was analysed and the results are shown on themap.

MAP SHOWING A SURVEY OF IRON CONCENTRATION IN RIVER SEDIMENTS

N

D

0 600300 1200 2000

Iron concentration of sediments (ppm)

kilometre

SCALE

0 1

KEY

Direction ofriver flow

(a) A known location of a primary ore deposit (D) is shown on the map.

On the map in your Section IV Answer Book, shade in the probable locations ofTWO other primary ore deposits.

(b) Assume that in the hydrothermal process, elemental iron reacts only with hydrogensulfide to form pyrite.

(i) Write the equation for this reaction.

(ii) Name the species that is being oxidised. Explain your choice.

20

30. (Continued)

In nature, pH and strength of oxidising/reducing environments determine which ironminerals precipitate. Diagram I shows the conditions under which various iron-containing minerals are stable.

6 7 8 9

Siderite(FeCO3)

Chamosite(Fe silicate)

Hematite(Fe2O3)

Limonite(Fe2O3.H2O)

0

Incr

easi

ngox

idis

ing

envi

ronm

ent

pHAcid Alkaline

Incr

easi

ngre

duci

ng e

nviro

nmen

t

Pyrite(FeS2)

DIAGRAM I

21

30. (Continued)

The rivers draining out of the mapped region contain a high concentration ofdissolved iron and flow into the sea. Three chemical environments in the sea areshown in Diagram II.

Sea level

X Y

Z

DIAGRAM II

X The water environment is oxidising and mildly alkaline near the shore.

Y The water is slightly reducing and mildly alkaline further from the shore.

Z The conditions are strongly reducing, and the water ranges from mildly acid tomildly alkaline in the deepest part of the ocean.

(c) Using information from Diagrams I and II, name an iron mineral that will be foundat:

(i) X;

(ii) Y;

(iii) Z .

(d) Wastes from mines containing pyrite have sometimes been dumped into dams. Thesulfide wastes react to produce a strongly acidic solution containing iron(III) oxide.

(i) Write the balanced equation for this reaction in the presence of oxygen.

(ii) Explain how seepage from such a dam could affect any surroundingagricultural area.

23

DATA SHEET

Values of several numerical constants

Avogadro’s constant, NA

Elementary charge, eFaraday constant, FGas constant, R

Mass of electron, meMass of neutron, mnMass of proton, mpVolume of 1 mole ideal gas

at 101·3 kPa (1 atm) andat 273 K (0°C)at 298 K (25°C)

6·022 × 1023 mol–1

1·602 × 10–19 C96 490 C mol–1

8·314 J K–1 mol–1

0·0821 L-atm K–1 mol–1

9·109 × 10–31 kg1·675 × 10–27 kg1·673 × 10–27 kg

22·41 L24·47 L

Earth’s gravitationalacceleration, g

Speed of light, cCoulomb’s constant, kPermeability constant, µ0

Universal gravitationconstant, G

Mass of EarthRadius of EarthPlanck’s constant, hDensity of waterSpecific heat capacity of

waterSpeed of sound in air

9·8 m s–2

3·00 × 108 m s–1

9·0 × 109 N m2 C2

4π × 10 –7 N A–2

6·7 × 10–11 N m2 kg–2

6·0 × 1024 kg6378 km6·626 × 10–34 J s1·00 × 103 kg m–3

4·18 × 103 J kg–1 K–1

340 m s–1

Some Standard Potentials

K+ + e– K(s) –2·94 V

Ba2+ + 2e– Ba(s) –2·91 V

Ca2+ + 2e– Ca(s) –2·87 V

Na+ + e– Na(s) –2·71 V

Mg2+ + 2e– Mg(s) –2·36 V

Al3+ + 3e– Al(s) –1·68 V

Mn2+ + 2e– Mn(s) –1·18 V

H2O + e– 12 H2(g) + OH– –0·83 V

Zn2+ + 2e– Zn(s) –0·76 V

S(s) + 2e– S2– –0·57 V

Fe2+ + 2e– Fe(s) –0·44 V

Ni2+ + 2e– Ni(s) –0·24 V

Sn2+ + 2e– Sn(s) –0·14 V

Pb2+ + 2e– Pb(s) –0·13 V

H+ + e– 12 H2(g) 0·00 V

SO42– + 4H+

+ 2e– SO2(aq) + 2H2O 0·16 V

Cu2+ + 2e– Cu(s) 0·34 V12 O2(g) + H2O + 2e– 2OH

– 0·40 V

Cu+ + e– Cu(s) 0·52 V12 I2(s) + e– I

– 0·54 V12 I2(aq) + e– I

– 0·62 V

Fe3+ + e– Fe2+ 0·77 V

Ag+ + e– Ag(s) 0·80 V

NO3– + 4H+ + 3e– NO(g) + 2H2O 0·96 V

12 Br2(l) + e– Br– 1·08 V12 Br2(aq) + e– Br– 1·10 V12 O2(g) + 2H+ + 2e– H2O 1·23 V

Cr2O72– + 14H+ + 6e– 2Cr3+ + 7H2O 1·36 V

12 Cl2(g) + e– Cl

– 1·36 V12 Cl2(aq) + e– Cl

– 1·40 V

MnO4– + 8H+ + 5e– Mn2+ + 4H2O 1·51 V

12 F2(g) + e–

F – 2·89 V

Alyward and Findlay, SI Chemical Data (3rd Edition) is the principal source of chemical data for thisexamination paper. Some data may have been modified for examination purposes.

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sci 3/4u core - board of studies

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