Secondary 3 Integrated Science Practice Paper: Cells, Separation, Forces, Energy, Acids And Earth And Space (100 Marks)

Secondary 3 Integrated Science Practice Paper: Cells, Separation, Forces, Energy, Acids and Earth and Space (100 marks)

2026-11-13

Integrated Science – Secondary 3 – Practice Paper

Secondary 3 integrated science practice paper, six sections and 24 parts: cells, separation, forces, energy, acids and Earth and space, with full answers and marks.

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Paper details　Secondary 3 integrated science practice paper with full answers: cells, separation, forces, energy, acids, Earth and space.

Section A: Cells and Life (16 marks)

The questions below are about cell structure, microscopes and cell division.

#	Question	Answer and marking notes
1	A microscope has a 15x eyepiece and a 40x objective lens. Find the total magnification.	Answer: 15 x 40 = 600 times. (Marking: setting up 2, answer 2)
2	At 600 times magnification a cell image is 3 mm long. Find the actual diameter in micrometres.	Answer: 3 / 600 = 0.005 mm = 5 micrometres. (Marking: division 2, unit conversion 2)
3	A cell divides every 30 minutes. Starting from 1 cell, how many cells are there after 2 hours?	Answer: 2 hours contains four 30-minute intervals, so there are 2 to the power 4 = 16 cells. (Marking: number of divisions 2, index calculation 2)
4	Name two structures found in plant cells but not in animal cells and give one function of each.	Answer: cell wall (supports the cell and keeps its shape); chloroplast (carries out photosynthesis to make food). (Marking: 2 per structure with its function)

Section B: Separating Substances (16 marks)

The questions below are about filtration, distillation, chromatography and solubility.

#	Question	Answer and marking notes
5	At 20 C, 50 g of water dissolves at most 18 g of potassium chloride. Find its solubility in g per 100 g of water at 20 C.	Answer: 18 x 2 = 36 g. (Marking: proportion 2, answer with unit 2)
6	Salt water is heated until all the water evaporates, leaving solid salt. Name this method and explain why filtration cannot separate salt from water.	Answer: evaporation to crystallisation. The salt is dissolved as very small particles spread evenly through the water, so the filter paper cannot trap them. (Marking: method 2, reason 2)
7	250 cm3 of a mixture contains 20% ethanol by volume. Find the volume of ethanol.	Answer: 250 x 0.20 = 50 cm3. (Marking: setting up 2, answer with unit 2)
8	In chromatography the distance from the origin to the solvent front is 8.0 cm and a pigment spot moves 4.8 cm. Find the Rf value of the pigment.	Answer: Rf = 4.8 / 8.0 = 0.60, which has no unit. (Marking: setting up 2, answer 2)

Section C: Forces and Motion (18 marks)

The questions below are about speed, acceleration, Newton second law, work and power.

#	Question	Answer and marking notes
9	A car travels 120 km in 1.5 hours. Find its average speed in km per hour.	Answer: 120 / 1.5 = 80 km per hour. (Marking: setting up 2, answer with unit 2)
10	A car accelerates uniformly from rest to 20 m per second in 8 seconds. Find the acceleration.	Answer: 20 / 8 = 2.5 metres per second squared. (Marking: setting up 2, answer with unit 2)
11	A car of mass 1500 kg accelerates at 2.5 metres per second squared. Find the resultant force.	Answer: F = ma = 1500 x 2.5 = 3750 N. (Marking: formula 2, substitution 2, answer with unit 1)
12	A worker pushes a box 12 m with a force of 300 N in the direction of motion, taking 6 seconds. Find the work done and the average power.	Answer: W = Fd = 300 x 12 = 3600 J; P = W / t = 3600 / 6 = 600 W. (Marking: work 2, power formula 2, answer with unit 1)

Section D: Energy and Circuits (18 marks)

The questions below are about electrical power, series circuits, efficiency and electricity cost.

#	Question	Answer and marking notes
13	A lamp is connected to a 12 V supply and the current is 0.5 A. Find its power and the energy it uses in 5 minutes, in joules.	Answer: P = VI = 12 x 0.5 = 6 W; E = Pt = 6 x 300 = 1800 J. (Marking: power 2, converting time to seconds 1, energy 2)
14	Resistors of 4 ohm and 6 ohm are connected in series to a 12 V supply. Find the total resistance and the current.	Answer: total resistance = 4 + 6 = 10 ohm; I = V / R = 12 / 10 = 1.2 A. (Marking: series addition 2, Ohm law 2, answer 1)
15	A machine takes in 500 J of energy and delivers 350 J of useful mechanical energy. Find the efficiency as a percentage.	Answer: 350 / 500 x 100 percent = 70 percent. (Marking: setting up 2, percentage 2)
16	An appliance rated 1.5 kW is used 4 hours a day. Find the daily energy use in kWh and the cost at 1.2 dollars per kWh.	Answer: 1.5 x 4 = 6 kWh; cost = 6 x 1.2 = 7.2 dollars. (Marking: kWh 2, cost 2)

Section E: Acids, Bases and Reactions (16 marks)

The questions below are about neutralisation, dilution, indicators and conservation of mass.

#	Question	Answer and marking notes
17	25.0 cm3 of 0.20 mol per dm3 sodium hydroxide is exactly neutralised by 0.10 mol per dm3 hydrochloric acid. Find the volume of acid needed in cm3.	Answer: moles of sodium hydroxide = 0.20 x 25.0 / 1000 = 0.005 mol; the ratio is 1 to 1, so the acid volume = 0.005 / 0.10 x 1000 = 50 cm3. (Marking: moles 2, ratio 1, volume 2)
18	A solution of pH 2 is diluted 100 times with water. Find the pH after dilution.	Answer: diluting 100 times lowers the hydrogen ion concentration 100 times, so pH rises by 2 units to pH = 4. (Marking: direction 1, value 2)
19	State the colour of phenolphthalein in acidic and in alkaline solution and explain why.	Answer: colourless in acid and pink in alkali. Phenolphthalein is an indicator whose molecules change structure at different pH, so they absorb different light. (Marking: 1 per colour, reason 2)
20	5.0 g of calcium carbonate reacts completely with 50 g of dilute hydrochloric acid and 2.2 g of carbon dioxide is released. Find the mass left and name the law used.	Answer: total mass of reactants = 5.0 + 50 = 55.0 g, so the mass left = 55.0 – 2.2 = 52.8 g; the law used is the conservation of mass. (Marking: total mass 2, subtraction 1, law 1)

Section F: Earth and Space (16 marks)

The questions below are about rotation of the Earth, the lunar cycle and eclipses.

#	Question	Answer and marking notes
21	The Earth takes 24 hours for one rotation. Find the angle it turns each hour.	Answer: 360 / 24 = 15 degrees. (Marking: setting up 2, answer with unit 2)
22	The lunar cycle lasts about 29.5 days. If it is divided into four equal phases, find the number of days between phases, to one decimal place.	Answer: 29.5 / 4 = 7.4 days. (Marking: setting up 2, one decimal place 2)
23	Explain how a solar eclipse happens and state the order of the three bodies involved.	Answer: the Moon moves between the Sun and the Earth, the three lie in a straight line, the Moon blocks the sunlight and its shadow falls on the Earth. The order is Sun, Moon, Earth. (Marking: positions 2, shadow or blocking 2)
24	List the four inner planets in order from the Sun and state which one is the largest.	Answer: Mercury, Venus, Earth, Mars; the Earth is the largest of the four. (Marking: order 3, largest 1)

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