Year 8 Sem 2 Science Exam 2020 PDF

Name: …………………………………………… Colour Class: ………………………………………. Class Teacher: ……………………………….. Caringbah High School Year 8 Science Exam...

Name: …………………………………………… Colour Class: ………………………………………. Class Teacher: ……………………………….. Caringbah High School Year 8 Science Exam Semester 2 2020 Write all your answers in this answer booklet. Use pen for written responses and pencil for diagrams and graphs. General Instructions Part A Multiple choice Questions 15 marks Working time – 60 minutes Part B Knowledge and Understanding 31 marks Write using blue or black pen Part C Working Scientifically 14 marks Draw diagrams using pencil Total Marks: 60 Approved calculators may be used Write your name and teacher’s name on the front of Attempt all questions in the space provided the paper Outcome Mark Total Score:________/60 Knowledge and Understanding / Exam Prepared by: K. Wynne Q Working Scientifically Q / PART A: Answer the multiple choice questions HERE. Circle the letter of the BEST answer. Do NOT detach this page from the rest of the exam. 1 A B X D 9 X B C D 2 A B X D 10 A B X D 3 A B X D 11 A B X D 4 A X C D 12 A B X D 5 A X C D 13 A B C X 6 A B C X 14 A B C X 7 A X C D 15 A B X D 8 X B C X Multiple Choice Total: ____________________ 19/9/23 Caringbah High School Science Faculty 1 PART A: Circle the letter of the BEST answer on the grid (15 marks) 1. Which option below is an acid commonly found in the home? A. Sodium Bicarbonate B. Nitric acid C. Citric acid D. Calcium Hydroxide 2. The chemical symbol that represents an atom with 19 protons is A. Potassium B. P C. K D. Phosphorus 3. A banksia plant has seed pods that are activated for germination by chemical and heat signals from combustion. This is an adaptation to A. Temperature B. Drought C. Bushfire D. Competition 4. What are the products of a reaction between an acid and a metal? A. Carbon dioxide, metal salt and water. B. Hydrogen gas and metal salt. C. Carbon dioxide and water. D. Metal salt and water. 5. Which of the following diagrams best models a mixture? A B C D 6. Shown in the circuit diagram below is 19/9/23 Caringbah High School Science Faculty 2  A. Two lamps and a resistor B. A lamp and a battery C. A switch and a lamp D. A switch, a lamp and a battery 7. Below is a food chain. The snake is described as a A. Primary consumer B. Tertiary consumer C. Producer D. Secondary consumer 8. What is the word equation that represents photosynthesis? A. Carbon dioxide + water  oxygen + glucose B. Carbon dioxide + glucose  oxygen + water C. water + glucose  carbon dioxide + oxygen D. water + carbon dioxide  oxygen + glucose 9. In an electric circuit diagram, what does this symbol represent? A. Voltmeter B. Ammeter C. Power source D. Lamp 10. Below are two graphs that shows biotic and abiotic data collected from coastal areas in Sydney, the Central Coast and the South Coast of NSW. The graphs show the coverage of kelp forests and the mass of sewage released into the ocean in these areas. 19/9/23 Caringbah High School Science Faculty 3  The conclusion you could come to, considering this data is A. Kelp forests are larger in Sydney, because sewerage discharge is low. B. Kelp forests are larger in Central Coast, because sewerage discharge is high. C. Kelp forests are lower in Sydney, because sewerage discharge is high. D. Kelp forests are lowest in South Coast, because sewerage discharge is high. 11. Which element from the list below is a non‐metal? A. Lithium B. Aluminium C. Carbon D. Tin 12. The following symbol was found on a container filled with an unknown chemical. What information about the chemical does this symbol give? A. It is corrosive. B. It is flammable. C. It is toxic. D. It is radioactive. 13. Which of the following is NOT an example of a physical change? A. Cutting paper. B. Boiling water. C. Sieving paperclips from sand. D. Baking a cake. 14. Which of the following is an abiotic environmental factor that measures acidity? A. Humidity B. Availability of food 19/9/23 Caringbah High School Science Faculty 4  C. Intensity of light D. pH 15. On the underside of most leaves, there is a small opening that allows for the exchange of gases. The name of this opening is A. Transpiration B. Xylem C. Stomate D. Phloem 19/9/23 Caringbah High School Science Faculty 5 PART B: Knowledge and Understanding 30 marks 16. Abundance can be measured using the capture‐mark‐recapture sampling technique. The following formula is used: 𝑁𝑜. 𝑖𝑛 𝑓𝑖𝑟𝑠𝑡 𝑐𝑎𝑝𝑡𝑢𝑟𝑒 𝑥 𝑁𝑜. 𝑖𝑛 𝑠𝑒𝑐𝑜𝑛𝑑 𝑐𝑎𝑝𝑡𝑢𝑟𝑒 𝐴𝑏𝑢𝑛𝑑𝑎𝑛𝑐𝑒 𝑁𝑜. 𝑚𝑎𝑟𝑘𝑒𝑑 𝑖𝑛 𝑠𝑒𝑐𝑜𝑛𝑑 𝑐𝑎𝑝𝑡𝑢𝑟𝑒 𝑟𝑒𝑐𝑎𝑝𝑡𝑢𝑟𝑒 Below is a table of data collected by using the capture‐mark‐recapture technique of the number of echidnas in an area of bushland. First Capture (No.) Second Capture (No.) Marked in Second Capture (No.) Echidna 15 12 5 a. Calculate the abundance of echidnas using the equation given. Show your working. 1 ………………………………………………………………………………………………………………………………………………………… 1 mark correctly calculates and shows working ………………………………………………………………………………………………………………………………………………………… Only answer: ………………………………………………………………………………………………………………………………………………………… 36 ………………………………………………………………………………………………………………………………………………………… Well answered! b. The actual number of echidnas in the population is 47. Give a reason why is there a difference 1 in the value you calculated compared with the actual population value. 1 mark correctly gives a reason about the nature of estimate, or the limitation of the technique ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… Sample: The value calculated is lower because the capture‐mark‐recapture technique is only a population estimate, not a direct count. ………………………………………………………………………………………………………………………………………………………… …………..…………………………………………………………………………………………………………………………………………… Sample: Animals can learn, so those in the first capture may avoid the second capture, so this interferes with the accuracy of the calculation. c. Outline how abundance is different to distribution. 2 1 mark defines abundance ………………………………………………………………………………………………………………………………………………………… 1 mark defines distribution ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… Sample answer: Abundance refers to the number of organisms in an area, but distribution is the location where the organism lives ………………………………………………………………………………………………………………………………………………………… Please be careful on working it is now ‘how’ they are located or ‘how’ many there are over a certain area. ………………………………………………………………………………………………………………………………………………………… 19/9/23 Caringbah High School Science Faculty 6 17. Below is a diagram of a model of the atom, based on the Bohr’s model. 2 Label on the diagram Neutron, Nucleus, Electron, Proton and orbit. 2 marks – all labels correct 1 mark – 1 label correct 0 marks – no labels correct Many students missed this question. Make sure you check the paper a) The atom shown contains 3 protons. Using the periodic table on the back of this paper, 1 mark identifies the atom. identify the atom shown.………………………………………………………………………………………………… Only choice ‐ Lithium 1 b) As part of this course you learned about different models of the atom. Identify the name of the scientist and describe one model of the atom you have learned about (other than the Bohr’s model). 3 ………………………………………………………………………………………………………………………………………………………… 1 mark identifies the name of a scientist ………………………………………………………………………………………………………………………………………………………… 2 marks describes key features of the model (‐1 mark for error) ………………………………………………………………………………………………………………………………………………………… Sample answer: Thompson developed the Plum Pudding Model. Negatively charged electrons (plum pieces) ………………………………………………………………………………………………………………………………………………………… embedded in a positively charged sphere (pudding) Students needed to match the right scientist with the right model for marks ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… c) Write the chemical formula for 1 mark per correct answer i) Sodium fluoride ……………………………………………………………………………………………………………. NaF 2 ii) Magnesium chloride …………………………………………………………………………………………………….. d) Give the scientific name for MgCl2 i) CaO ………………………………………………………………………………………………………………………………. Calcium oxide 2 ii) Li2S……………………………………………………………………………………………………………………………….. Lithium Sulfide 19/9/23 Caringbah High School Science Faculty 7 18. A student read a paragraph about the relationships of some animals and plants in an area known as Outskirtsville. “In Outskirtsville, farmers grow crops of grains and carrots. The farmers are experiencing some difficulty because they are overrun with pests. They regularly have to spray their crops to inhibit the growth of invasive grasses, and leave out baits for mice and rabbits which eat the crop. The presence of mice and rabbits attracts foxes and owls, who feed on the pests. The foxes also eat the owls, so farmers have to leave traps out to catch the foxes, because the owls are a protected species. Occasionally, the farmers catch small birds in their traps. The birds are attracted to eat insects like grasshoppers, which eat the invasive grasses and grains.” Below is a diagram with the organisms from the paragraph labelled. 1 mark – arrows point in right direction (from prey to predator) 1 mark – relationships correct as shown 2 a. On the image above, use arrows to create a food web that shows the relationships as they are outlined in the paragraph. b. There are a number of symbiotic interactions depicted in the diagram above. Identify an interaction/organism that best fits the interactions described. 1 i. Herbivory is the consumption of plant material by animals. correct interpretation as per diagram 1 mark each ………………………………………………………………………………………………………………………………………………………… Sample: Herbivory – rabbits eating carrots/grains 1 Make is ii. Interspecific competition sure anyou state the full interaction relationship where two organisms of different species compete for the same resource. Interspecific competition – owls and foxes eating rabbits 2 ………………………………………………………………………………………………………………………………………………………… c. Define mutualism, using an example of your choice (you do not need to use the diagram). ………………………………………………………………………………………………………………………………………………………… 1 mark correct definition ………………………………………………………………………………………………………………………………………………………… 1 mark correct example ………………………………………………………………………………………………………………………………………………………… Sample: Mutualism is a relationship where both organisms benefit. Example is bees and flowering plants – the bees get pollen for honey making/food, and they distribute the pollen from plant to plant for its reproduction. Needs to be a close relationship not a distant relationship. 19/9/23 Caringbah High School Science Faculty 8 19. A scientist was working to investigate the growth of microorganisms over time. a) Identify a disease caused by a harmful microorganism. 1 1 mark appropriate disease identified. ………………………………………………………………………………………………………………………………………………………… Sample: Tetanus b) Describe one way you can prevent contamination with microorganisms in the home. 1 1 mark appropriate precaution identified. ………………………………………………………………………………………………………………………………………………………… Sample: Wash your hands after handling raw foods ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… c) Below is a graph produced by the scientist that shows the number of bacteria on an agar plate over time. 2 The scientist noticed that the growth of bacteria was increasing at a steady rate and then a change occurred in the growth, as indicated by the dotted line. Describe what might have happened that would result in the change shown in the graph after the dotted line. 1 mark identify appropriate change. ………………………………………………………………………………………………………………………………………………………… 1 mark provides detail ………………………………………………………………………………………………………………………………………………………… Sample: Bacteria numbers got so high that the population ran out of resources (like food) so they started dying off. ………………………………………………………………………………………………………………………………………………………… Other answers might include the introduction of antibiotics, change in temperature etc. ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… 19/9/23 Caringbah High School Science Faculty 9  d) Assess means to “make a judgement of value, quality, outcomes, results or size”. When we write assessments in Science, it is useful to describe a positive, describe a negative and then make a judgement. 3 Assess the use of antibiotics on the health of humans. ………………………………………………………………………………………………………………………………………………………… 1 mark positive ………………………………………………………………………………………………………………………………………………………… 1 mark negative 1 mark judgement ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… Sample: After their discovery, antibiotics were used to treat a wide range of common diseases and ailments such ………………………………………………………………………………………………………………………………………………………… as tonsillitis and ear infections which increased the health of the population overall very quickly. Unfortunately, the overuse and misuse of antibiotics lead to the development of antibiotic resistance, and now previously ………………………………………………………………………………………………………………………………………………………… treatable diseases can’t be treated at all, such as multidrug resistant Staphylococcus aureus (MRSA). Overall, ………………………………………………………………………………………………………………………………………………………… antibiotics have a specific use in improving the health of humans, and can continue to be used to improve health, provided their use is considered and controlled. ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………………………………… 20. a. Compare two properties of acids and bases. ………………………………………………………………………………………………………………………………………………………… 2 1 mark for each comparison (2 marks total) ………………………………………………………………………………………………………………………………………………………… Sample answer: ………………………………………………………………………………………………………………………………………………………… ACID BASE ………………………………………………………………………………………………………………………………………………………… Taste Sour Bitter pH Below 7 Above 7 ………………………………………………………………………………………………………………………………………………………… Damage Corrosive Caustic b. A neutralisation reaction is a reaction between an acid and base. Write the chemical word 2 equation for a neutralisation reaction between sulfuric acid and potassium hydroxide. ………………………………………………………………………………………………………………………………………………………… 2 marks for correct answer (‐1 mark for error, eg incorrect products, e.g. potassium sulfide?) ………………………………………………………………………………………………………………………………………………………… Sulfuric acid + potassium hydroxide  Potassium sulfate + Water ………………………………………………………………………………………………………………………………………………………… Few students achieved 2 marks in this question as they were required to write both products (Potassium sulfate) 19/9/23 Caringbah High School Science Faculty 10 PART C: Working Scientifically 15 marks 21. Below is a diagram that shows an experiment that a student conducted to measure the volume of gas produced during a chemical reaction. The student took 30g of calcium carbonate, and reacted it with different volumes of hydrochloric acid. The results are shown in the table below. Volume of Hydrochloric acid (mL) Volume of gas collected (mL) 8 30 12 60 33 90 120 58 150 75 a) Write a hypothesis that could be tested with this experiment. ………………………………………………………………………………………………………………………………………………………… 1 mark appropriate hypothesis 1 Sample: As the volume of acid is increased, the volume of gas will also increase ………………………………………………………………………………………………………………………………………………………… b) Write a risk assessment statement for the most significant risk in this experiment. 1 ………………………………………………………………………………………………………………………………………………………… 1 mark appropriate risk assessment Sample: Hydrochloric acid is corrosive and can cause burns to eyes. Wear goggles. ……………………………………………………………………………………………………………………………………………………… c) When the student reacts the hydrochloric acid and calcium carbonate together, the gas is 1 produced alongside a salt (calcium chloride) and water. Write a word equation to represent this reaction. ………………………………………………………………………………………………………………………………………………………… 1 mark appropriate word equation with + and  symbols Sample: hydrochloric acid + calcium carbonate  calcium chloride + water + carbon dioxide ………………………………………………………………………………………………………………………………………………………… d) Describe one controlled variable. 1 ………………………………………………………………………………………………………………………………………………………… 1 mark appropriate controlled variable described ………………………………………………………………………………………………………………………………………………………… Sample: mass of calcium carbonate e) The student wants to ensure that their experiment is reliable. What should they do and how will they know it’s reliable? 2 ………………………………………………………………………………………………………………………………………………………… 1 mark appropriate aspect of reliability to do 1 mark appropriate aspect of reliability to know ………………………………………………………………………………………………………………………………………………………… Sample: The student should repeat the experiment several times. When they look at the results, the values should ………………………………………………………………………………………………………………………………………………………… be similar if it is reliable. ……………………………………………………………………………………………………………………………………………………. 19/9/23 Caringbah High School Science Faculty 11 22. A student at CHS investigated the electrical efficiency of four household devices. To calculate electrical efficiency, the student needed to measure the input energy and the output energy for each device, as shown in the table below. The student needs to include one more column to the results table, that shows the electrical efficiency. Efficiency is measured using the following formula. 𝑥 100 = efficiency % a) Complete the table below by calculating the efficiency of all four devices. 1 mark heading with unit 3 2 marks all values calculated correctly (1 mark if 1 error) Efficiency (%) 30 22.5 27 53.7 1 b) Rank the devices from most efficient to least efficient. 4>1>3>2 ………………………………………………………………………………………………………………………………………………………… c) Graph the student’s results for electrical efficiency vs device number using a column graph. 4 Note: in a column graph, spaces should be left between each column. Scale Axis 19/9/23 Caringbah High School Science Faculty 12 Science Assessment Task Reflection Sheet Student name: _____________________________ Year: ___________________________ Task Name: _________________________ Semester: _________________________________ Mark:___/____ Class Work Personal Study Exam Performance Future planning Did I pay attention in class? Did I take Did I revise all notes, topics, Did I read and understand the What will I do differently next time? effective notes? Did I complete all class terminology/ Did I practise any questions? Did I write with correct How can I improve? Could I ask more in work? questions? Did I take responsibility for grammar and spelling? Did I write questions in class? my own learning? succinctly? Was my handwriting legible? Did I pursue my personal best? Knowledge and Understanding Practical Skills Problem Solving Skills Literacy Numeracy COMMENTS: Write, draw a picture, make a list, etc 19/9/23 Caringbah High School Science Faculty 1 Polyatomic Ions and Valency’s Polyatomic Ion Charge = -1 bicarbonate (or hydrogen carbonate) - HCO3- hydroxide - OH- nitrate - NO3- Polyatomic Ion Charge = -2 sulfate - SO42- carbonate - CO32- Polyatomic Ion Charge = -3 phosphate - PO43- Metal Ions Iron ‐ Fe2+ or Fe3+ Copper – Cu1+ or Cu2+ Lead ‐ Pb2+ or Pb4+ Zinc ‐ Zn2+ Tin ‐ Sn2+ or Sn4+ 19/9/23 Caringbah High School Science Faculty 1