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O Level Combined Science Practice Paper 2
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TuitionGoWhere Practice Paper - Combined Science O-Level
TuitionGoWhere Practice Paper (AI)
Subject: Combined Science (Physics, Chemistry) Level: O-Level Paper: Practice Paper – Physical Sciences Version: 2 of 5 Duration: 1 hour 15 minutes Total Marks: 65
Name: _________________________ Class: _________________________ Date: _________________________
Instructions to Candidates
- This paper consists of two sections: Section A and Section B.
- Answer all questions in both sections.
- Write your answers in the spaces provided.
- Show all working for calculation questions. Marks are awarded for correct method.
- The number of marks is given in brackets [ ] at the end of each question or part question.
- You may use a calculator.
- Take g = 10 N/kg where necessary.
Section A: Physics (32 marks)
Answer all questions in this section.
1. A student measures the length of a laboratory bench using a metre rule. She records the length as 1.85 m.
(a) State the precision of the metre rule used. [1]
(b) The student measures the width of the bench as 0.62 m. Calculate the area of the bench top. Give your answer to an appropriate number of significant figures. [2]
2. A car travels along a straight road. The graph below shows how its velocity changes with time during the first 30 seconds of its journey.
(Imagine a velocity-time graph: velocity increases uniformly from 0 to 20 m/s in the first 10 s, stays constant at 20 m/s from 10 s to 25 s, then decreases uniformly to 0 m/s from 25 s to 30 s.)
(a) Describe the motion of the car between 10 s and 25 s. [1]
(b) Calculate the acceleration of the car during the first 10 seconds. [2]
(c) Calculate the total distance travelled by the car in the 30 seconds. [3]
3. A wooden block of mass 2.0 kg rests on a horizontal table. A horizontal force of 6.0 N is applied to the block, but it does not move.
(a) State the size of the frictional force acting on the block. Explain your answer. [2]
(b) The applied force is increased to 10.0 N and the block begins to move with constant velocity. State the size of the frictional force now acting on the block. [1]
(c) Explain why the frictional force in part (b) is different from the frictional force in part (a). [2]
4. A uniform plank of weight 200 N is placed on a pivot at its centre. A 150 N weight is placed 1.2 m to the left of the pivot.
(a) State the principle of moments. [1]
(b) Calculate the distance from the pivot where a 100 N weight must be placed on the right side to balance the plank. [3]
5. A rectangular block of metal measures 0.20 m × 0.15 m × 0.10 m and has a mass of 24 kg.
(a) Calculate the volume of the block. [1]
(b) Calculate the density of the metal in kg/m³. [2]
(c) The block is placed on a table with its largest face in contact with the table surface. Calculate the pressure exerted by the block on the table. [3]
6. A student investigates the transfer of thermal energy. She sets up the apparatus shown below.
(Imagine a diagram: a metal rod with one end in a beaker of boiling water. Wax-coated drawing pins are stuck at equal intervals along the rod.)
(a) State the main process by which thermal energy is transferred along the metal rod. [1]
(b) Explain, using the particle model, how this transfer occurs in a metal. [3]
(c) The student repeats the experiment using a glass rod of the same dimensions. State and explain how the result would differ. [2]
Section B: Chemistry (33 marks)
Answer all questions in this section.
7. The table below gives information about four particles: A, B, C, and D.
| Particle | Number of protons | Number of neutrons | Number of electrons |
|---|---|---|---|
| A | 8 | 8 | 8 |
| B | 8 | 9 | 8 |
| C | 8 | 8 | 10 |
| D | 11 | 12 | 10 |
(a) Which two particles are isotopes of the same element? Explain your answer. [2]
(b) Which particle is a negatively charged ion? Explain your answer. [2]
(c) Particle D is an ion of sodium. Write the symbol for this ion, showing its mass number and atomic number. [2]
8. Magnesium reacts with oxygen to form magnesium oxide.
(a) State the type of bonding present in magnesium oxide. [1]
(b) Draw a 'dot-and-cross' diagram to show the bonding in magnesium oxide. Show only the outer shell electrons. [3]
(Use the space below for your diagram)
(c) Magnesium oxide has a very high melting point. Explain why. [2]
9. A student prepares a sample of copper(II) sulfate crystals by reacting excess copper(II) oxide with warm dilute sulfuric acid.
(a) Write a balanced chemical equation for the reaction between copper(II) oxide and sulfuric acid. [2]
(b) State what the student would observe during the reaction. [1]
(c) Describe the steps the student should take to obtain pure, dry copper(II) sulfate crystals from the reaction mixture. [4]
10. 5.6 g of iron reacts completely with excess dilute hydrochloric acid according to the equation:
Fe + 2HCl → FeCl₂ + H₂
(Aᵣ: Fe = 56; molar volume of gas at r.t.p. = 24 dm³/mol)
(a) Calculate the number of moles of iron used. [1]
(b) Calculate the volume of hydrogen gas produced at room temperature and pressure. [2]
(c) The experiment is repeated using the same mass of iron powder instead of iron filings. State and explain how the rate of reaction would differ. [2]
11. A student investigates the reaction between marble chips (calcium carbonate) and dilute hydrochloric acid. The reaction produces carbon dioxide gas.
CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g)
The student measures the volume of gas produced every 30 seconds. The results are shown in the table below.
| Time / s | 0 | 30 | 60 | 90 | 120 | 150 | 180 | 210 | 240 |
|---|---|---|---|---|---|---|---|---|---|
| Volume of CO₂ / cm³ | 0 | 28 | 48 | 62 | 72 | 78 | 82 | 84 | 84 |
(a) Plot a graph of volume of carbon dioxide (y-axis) against time (x-axis) on the grid below. [4]
(Use the space below for your graph)
(b) Use your graph to determine the volume of gas produced after 75 seconds. [1]
(c) Calculate the average rate of reaction, in cm³/s, between 0 and 60 seconds. [2]
(d) The experiment is repeated at a higher temperature. On your graph, sketch the curve you would expect. Label this curve 'T'. [2]
(e) Explain, using collision theory, why increasing the temperature increases the rate of reaction. [2]
12. Ethene (C₂H₄) is an unsaturated hydrocarbon.
(a) State what is meant by the term unsaturated in the context of hydrocarbons. [1]
(b) Describe a chemical test that can be used to distinguish between ethene and ethane. State the reagent used and the observation for each gas. [3]
(c) Ethene can undergo addition polymerisation to form poly(ethene). Draw the repeating unit of poly(ethene). [2]
END OF PAPER
Answers
TuitionGoWhere Practice Paper - Combined Science O-Level Answers
Section A: Physics
1.
(a) 0.01 m or 1 cm [1]
(b) Area = length × width = 1.85 m × 0.62 m = 1.147 m² ≈ 1.1 m² (to 2 sig. fig. as 0.62 has 2) [2]
2.
(a) Constant velocity / uniform motion (moving at 20 m/s) [1]
(b) a = (v - u)/t = (20 - 0)/10 = 2.0 m/s² [2]
(c) Distance = area under graph:
0–10 s: triangle = ½ × 10 × 20 = 100 m
10–25 s: rectangle = 15 × 20 = 300 m
25–30 s: triangle = ½ × 5 × 20 = 50 m
Total = 100 + 300 + 50 = 450 m [3]
3.
(a) 6.0 N. The block is stationary, so net force is zero; friction equals applied force. [2]
(b) 10.0 N [1]
(c) In (a) static friction acts; it matches applied force up to a limit. In (b) the block moves at constant velocity, so kinetic friction equals applied force. Static friction (max) > kinetic friction, but here the 6 N wasn't the maximum; the change occurs because once moving, friction drops slightly. Accept explanation that static friction can vary, kinetic friction is constant. [2]
4.
(a) For a body in equilibrium, the sum of clockwise moments about any point equals the sum of anticlockwise moments about the same point. [1]
(b) Let distance for 100 N on right be d.
Anticlockwise moment = 150 N × 1.2 m = 180 Nm
Clockwise moment = 100 N × d
For balance: 100d = 180 → d = 1.8 m [3]
5.
(a) Volume = 0.20 × 0.15 × 0.10 = 0.0030 m³ [1]
(b) Density = mass/volume = 24 / 0.0030 = 8000 kg/m³ [2]
(c) Largest face area = 0.20 × 0.15 = 0.030 m²
Weight = 24 × 10 = 240 N
Pressure = force/area = 240 / 0.030 = 8000 Pa [3]
6.
(a) Conduction [1]
(b) Free electrons gain kinetic energy from hot end, move and collide with other atoms/ions, transferring energy. The lattice vibrations also pass energy. [3]
(c) The glass rod would conduct much slower because glass lacks free electrons; thermal energy transfer relies only on lattice vibrations (phonons), which are less efficient. [2]
Section B: Chemistry
7.
(a) A and B are isotopes: same number of protons (8) but different neutrons (8 and 9). [2]
(b) Particle C: 8 protons (+) and 10 electrons (−), net charge −2, so a negative ion. [2]
(c) Symbol: (\ce{^{23}_{11}Na^+}) (mass number 11+12=23, atomic number 11, charge +1) [2]
8.
(a) Ionic bonding [1]
(b) Dot-and-cross: Mg with no outer electrons (after loss), O with 8 outer electrons (dots/crosses) arranged around it, with brackets and charges: [Mg]²⁺ [O]²⁻. Show electron transfer: Mg loses two electrons, O gains two. [3]
(c) Giant ionic lattice structure; strong electrostatic forces of attraction between oppositely charged ions require a lot of energy to overcome. [2]
9.
(a) CuO(s) + H₂SO₄(aq) → CuSO₄(aq) + H₂O(l) [2]
(b) Black solid dissolves, forming a blue solution. [1]
(c) Filter to remove unreacted CuO; heat filtrate gently to evaporate some water to obtain a saturated solution; leave to cool and crystallise; filter crystals and dry between filter paper. [4]
10.
(a) Moles Fe = 5.6 / 56 = 0.10 mol [1]
(b) 1 mol Fe produces 1 mol H₂, so 0.10 mol H₂. Volume = 0.10 × 24 = 2.4 dm³ [2]
(c) Iron powder has larger surface area than filings; more frequent collisions between particles, rate of reaction increases. [2]
11.
(a) Graph: Axes labelled correctly, points plotted accurately, smooth curve drawn. [4]
(b) From graph at 75 s, volume ≈ 55 cm³ (accept 54–56). [1]
(c) Average rate = (48 - 0) / 60 = 0.80 cm³/s [2]
(d) Steeper initial slope, same final volume plateau, labelled 'T'. [2]
(e) Higher temperature increases kinetic energy of particles, more collisions have energy ≥ activation energy, and more frequent collisions, so faster rate. [2]
12.
(a) Contains at least one carbon–carbon double bond. [1]
(b) Add bromine water (orange); with ethene it decolourises (turns colourless); with ethane it remains orange/no change. [3]
(c) Repeating unit: —[CH₂—CH₂]— or structural diagram with single bonds. [2]