PAPER. Practice Questions SCIENCE. International Competitions and Assessments for Schools STUDENT S NAME: DO NOT OPEN THIS BOOKLET UNTIL INSTRUCTED.

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1 ractice uestions nternational ompetitions and ssessments for chools U U. U : ead the instructions on the and fill in your, and. Use a 2 or pencil. o use a pen. ub out any mistakes completely. ou U record your answers on the. ark only answer for each question. our score will be the number of correct answers. arks are deducted for incorrect answers. Use the information provided to choose the answer from the four possible options. n your fill in the oval that matches your answer. ou may use a calculator and a ruler.

2 or questions and 2 use the information below. he graph shows the relationship between muscle fibre length and tension. he shaded band represents the range of muscle lengths that can occur in the body without the muscles detaching from the bones. ercentage of maximum tension ercentage of optimal muscle length. ver what percentage of optimal length can a muscle vary without detaching from the bones? () 46% () 67% () 73% () 84% 2. hich option best summarises the information in the graph? he tension developed by a muscle fibre when it is stimulated () () () () increases as the length of the fibre increases from shorter-than-optimal to optimal length, then decreases as the length exceeds optimal. increases as the length of the fibre increases from shorter-than-optimal length, then continues to increase as the length exceeds optimal. decreases as the length of the fibre increases from shorter-than-optimal to optimal length, then decreases again as the length exceeds optimal. decreases as the length of the fibre increases from shorter-than-optimal to optimal length, then increases again as the length exceeds optimal. 3. he two graphs below show what scientists believe were the concentrations of nitrogen and carbon dioxide in the atmosphere between 4 5 million and 2 million years ago. itrogen in arths atmosphere (%) ime (millions of years ago) arbon dioxide in arths atmosphere (%) ime (millions of years ago) here was a time in history when carbon dioxide and nitrogen were present in equal percentages in the atmosphere. t what time did this occur? () 2 million years ago () 35 million years ago () 43 million years ago () 45 million years ago cience ractice uestions aper 2

3 4. ome molecules are mirror images of each other. hey cannot be rotated or moved so that one molecule can be superimposed on the other. he models of molecules shown are mirror images of each other. ere is a model of a molecule of -iodoethanol. hich model of a molecule below is a mirror image of the one above? () () () () 3 cience ractice uestions aper

4 or questions 5 and 6 use the information below. n forensic science, blood alcohol content is tested at the time of sampling and, if challenged in court, from a stored sample. student wanted to know how the tightness of the lid of a screw-topped container affected the loss of alcohol over time. e assumed alcohol behaved the same way in blood and water. e partially filled three containers with equal quantities of. g alcohol solution. e then tightened the lids as follows. loose lid - tighten until resistance is experienced then turn lid back mm. firm lid - tighten until resistance is just experienced. tight lid - tighten until resistance is just experienced then turn a further mm forward. he solutions were then stored in a storage cabinet at 3 for a number of weeks. is results are shown in the graph. lcohol concentration (g ) eek eek eek 3 eek 5 eek 7 tanding time loose firm tight 5. y how many grams per litre has the concentration dropped after three weeks in the container with the tight lid? ().5 (). ().9 () hich hypothesis best applies to this experiment? () () () () lood reacts with alcohol over time. lood kept in sealed containers should not be used in court. hanges in blood alcohol concentration are due to lid tightness. hanges in temperature affect blood alcohol concentration. cience ractice uestions aper 4

5 or questions 7 and 8 use the information below. frogs body temperature varies with its surroundings. hese two graphs compare the body temperatures of some frogs with the temperature of their surroundings. 4 4 ody temperature ( ) ody temperature ( ) round temperature ( ) ir temperature ( ) ach dot represents the measured values taken for each individual frog. he straight line on each graph is called the isothermal line. hat does it represent? () () () () the dividing line separating the frogs into two equal groups the line joining points where body temperature equals surrounding temperature the ratio of average body temperature to surrounding temperature the average body temperature of frogs at various surrounding temperatures 8. student drew the following inferences: ore than 5% of frogs have a body temperature higher than the air temperature. frogs body temperature increases as the temperature of its surroundings increases. he air temperature is lower than ground temperature. hich inference(s) isare supported by the graphs? () () () () only only and only,, and 5 cience ractice uestions aper

6 9. he density of any substance is given by the equation mass density = volume olume (cm 3 ) he graph shows the volume of one gram of water in the temperature range from to. hen a pond cools, water from the surface sinks to the bottom because of its greater density emperature ( ) = bottom = surface s the temperature of the air above the water drops below, the surface of the water freezes. he temperature of the ice formed stays at as more water freezes. hich of the graphs below shows the temperature at different depths in a pond of water as the surface freezes over? () () () (). hen a liquid in a mixture evaporates, any dissolved solids are left behind. he oxhlet extractor works very well to extract chlorophyll from leaves using a flammable solvent. here are seven steps in the process.. he leaves are placed in a sieve. 2. he solvent evaporates and passes up through the bypass sidearm. 3. he solvent vapour enters the condenser. 4. he condenser liquefies the solvent which is now pure. 5. he liquid drops into the sieve and dissolves chlorophyll from the leaves. 6. hen the liquid fills up to the top of the reflux sidearm, it is all siphoned back into the flask. 7. olvent and chlorophyll collect in the flask. he process repeats until the apparatus is switched off. hich of the following statements explains why the oxhlet extractor works so well? water out bypass sidearm flask condenser water in pure solvent reflux sidearm sieve solvent + chlorophyll heat source () () () () oisonous or flammable solvents can be used safely. he extracting solvent is always near boiling point. he solvent is constantly purified before re-use. he extracted solute collects in the flask. cience ractice uestions aper 6

7 his page may be used for working. 7 cience ractice uestions aper

8 cknowledgment opyright in this booklet is owned by ducational ssessment ustralia, U lobal ty imited, unless otherwise indicated. very effort has been made to trace and acknowledge copyright. ducational ssessment ustralia apologises for any accidental infringement and welcomes information to redress the situation. he following year levels should sit aper: ustralia ear 2 runei re-university 2 alaysia Upper 6 ew ealand ear 3 acific ear 2 ingapore unior ollege outh frica rade 2 U U ducational ssessment ustralia eaa.unsw.edu.au 2 ducational ssessment ustralia. is an education group of U lobal ty imited, a not-for-profit provider of education, training and consulting services and a wholly owned enterprise of the University of ew outh ales

9 to appear on certificate to appear on certificate re you male or female? ale emale oes anyone in your home usually speak a language other than nglish? es o chool name: own suburb: odays date: ostcode: ay onth ear (optional) U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U U : ub out all mistakes completely. rint your details clearly in the boxes provided. ake sure you fill in only one oval in each column. : ebbie ach 2: han i eng 3: amal bin bas U U *4562* aper nternational ompetitions and ssessments for chools U

10 U xample: ri added cordial to water to make a jug of drink. hat will be the volume of the drink in the jug? () () () () 5 m 5 m 2 m 25 m he answer is 25 m, so you would fill in the oval, as shown our privacy is assured as fully complies with appropriate ustralian privacy legislation. isit for more details. aper nternational ompetitions and ssessments for chools

11 U key reasoning U he shaded area extends from 7% to 3%. asy 2 3 he graph shows that tension increases to % of optimal length and once this length is exceeded (>%) tension starts to decrease. f the graphs are plotted on the same set of axes, they will cross at approximately 4 3 million years ago asy asy 4 is identical to the original, so is wrong. is the same as but it is has been flipped and rotated, so is wrong. is the same as but has been further rotated, so is wrong. odels, and are all ()--iodoethanol. ompare and the original; the blue atom is in a different position. is a different chemical, and is called ()--iodoethanol. hese are optical isomers. asy he tight column in the graph shows that after three weeks the concentration in the tight lidded container dropped from. g - to approximately.95 g - which is a difference of.5 g -. lease note that the question asks for the difference after three weeks and not seven weeks. n the experiment the tightness of the lid has been altered (loose, firm, and tight) and change in alcohol concentration was measured. rom the graphs, the lines join points where body temperature equals the surrounding temperature. nference can be drawn from the air-body temperature graph. nference can be drawn from both graphs. nference is not supported by these graphs as there is nothing to relate air temperature to ground temperature. herefore option is correct. rom the volume versus temperature graph, it can be seen that at water is less dense than at 4, which is the temperature where water has its maximum density. his means that the surface of the freezing pond is at and the bottom is at 4. ecause pure solvent is always entering the sieve dissolving any chlorophyll remaining in the leaves, the maximum amount of chlorophyll will be extracted from the leaves. ediumard asy ediumard edium ard ard cience ractice uestions aper

12 evel of difficulty refers to the expected level of difficulty for the question. asy edium ediumard ard more than 7% of candidates will choose the correct option. about 57% of candidates will choose the correct option. about 35% of candidates will choose the correct option. less than 3% of candidates will choose the correct option. cience ractice uestions aper