S2 Integrated Science Practice Paper (Set 2): Particle Model, Separation Techniques, Pressure, Energy And Circuits, Earth And Space, Experimental Design

S2 Integrated Science Practice Paper (Set 2): Particle Model, Separation Techniques, Pressure, Energy and Circuits, Earth and Space, Experimental Design

2026-11-15

S2 Integrated Science

S2 Integrated Science, Set 2: particle model and density, separation, pressure and buoyancy, series circuits, Earth and lunar phases, fair-test data. 24 parts, 100 marks.

Paper details　S2 Integrated Science practice paper (Set 2): particle model, density, separation techniques, pressure, buoyancy, series circuits, Earth and moon, data recording.

Section A: Matter and the Particle Model

Study each item and answer the questions.

#	Question	Answer and marking notes
1	A beaker holds 250 cm3 of pure water of density 1.0 g/cm3. 30 g of salt is added and dissolves completely. Find the total mass of the solution in g and name the mass relationship you use.	Answer: 280 g. Water 250 g plus salt 30 g; total mass does not change on dissolving (conservation of mass).
2	A fixed mass of gas is compressed from 0.60 m3 to 0.20 m3 at constant temperature with no change in the number of particles. How many times larger is the number of particles per unit volume?	Answer: 3 times. 0.60 divided by 0.20 is 3; the volume falls to one third, so the particle density rises threefold.
3	A metal block has a mass of 216 g and a volume of 80 cm3. Calculate its density in g/cm3 and name the metal whose density is 2.7 g/cm3.	Answer: 2.7 g/cm3. 216 divided by 80 is 2.7, which matches aluminium, so the metal is most likely aluminium.
4	A drop of blue ink is placed in still water. When the water is warmed from 20 degrees C to 60 degrees C the ink spreads noticeably faster. Explain this with the particle model.	Answer: At the higher temperature the average kinetic energy of the water particles rises, they move faster and collide with the ink particles more often, so the ink spreads faster.

Section B: Separation Techniques

The items below involve separating mixtures. Calculate and answer.

#	Question	Answer and marking notes
5	A 50.0 g mixture of sand and salt is dissolved in water and filtered. The filtrate is evaporated to dryness to give 3.5 g of salt, and the sand left on the paper is 46.5 g. Check the sum of the two masses.	Answer: 46.5 g plus 3.5 g gives 50.0 g, equal to the original mixture; no matter is lost in the process.
6	Simple distillation of 120 cm3 of a water-ethanol mixture gives 85 cm3 of distillate. Find the volume left in the flask and state what kind of mixture distillation separates.	Answer: 120 minus 85 gives 35 cm3. Distillation separates miscible liquids that have different boiling points, such as water and ethanol.
7	In chromatography a spot rises 6.0 cm from the start line while the solvent front travels 9.6 cm from the same line. Calculate the Rf value to three significant figures.	Answer: Rf equals 6.0 divided by 9.6, that is 0.625. Under fixed conditions the Rf value helps identify a substance.
8	Which separation method is used to obtain solid salt from sea water? Give a brief reason.	Answer: Evaporation to crystallisation. Heating removes water as vapour while the salt does not evaporate, so solid salt is left behind.

Section C: Force and Pressure

Take g as 10 N/kg and the density of water as 1000 kg/m3.

#	Question	Answer and marking notes
9	A student weighs 480 N and stands on both feet with a total contact area of 0.030 m2. Calculate the pressure he exerts on the floor in Pa.	Answer: Pressure equals 480 divided by 0.030, that is 16000 Pa, or 16 kPa.
10	The same student then stands on one foot, so the contact area becomes 0.015 m2. Find the new pressure and explain the change.	Answer: The pressure is 480 divided by 0.015, that is 32000 Pa. The force is unchanged while the area halves, so the pressure doubles.
11	A container holds water to a depth of 0.25 m. Calculate the pressure the water exerts on the bottom in Pa.	Answer: Pressure equals 1000 times 10 times 0.25, that is 2500 Pa.
12	A wooden block of volume 200 cm3 and density 0.6 g/cm3 floats on water. Find its mass in g, its weight in N and the volume of water it displaces in cm3.	Answer: Mass is 0.6 times 200, that is 120 g; weight is 0.12 kg times 10, that is 1.2 N. A floating body displaces its own weight, so 120 cm3 of water.

Section D: Energy Transfer and Circuits

The resistance of each resistor is given. Work through the steps.

#	Question	Answer and marking notes
13	Resistors of 4 ohm, 6 ohm and 2 ohm are connected in series to a 12 V supply. Find the total resistance in ohm and the current in A.	Answer: Total resistance is 4 plus 6 plus 2, that is 12 ohm; current is 12 divided by 12, that is 1.0 A.
14	The circuit runs for 5 minutes. Find the total power of the supply in W and the energy transferred in J.	Answer: Power is 12 times 1.0, that is 12 W; energy is 12 times 300, that is 3600 J.
15	A 60 W lamp converts only 25% of its electrical energy into light. Find the useful light energy produced in 5 minutes in J.	Answer: Useful power is 60 times 0.25, that is 15 W; useful light energy is 15 times 300, that is 4500 J, and the rest becomes heat.
16	Household appliances are mostly connected in parallel. Explain the advantage of a parallel circuit using a broken lamp as the example.	Answer: In a parallel circuit each branch is independent; when one lamp fails the other branches still carry current, so the other appliances keep working and each one receives the full supply voltage.

Section E: Earth and Space

Answer using the data given.

#	Question	Answer and marking notes
17	On a certain day sunrise in Hong Kong is at 06:12 and sunset at 18:48. Find the hours of daylight, and check your answer in minutes.	Answer: Daylight lasts 756 minutes, that is 12.6 hours, or 12 hours 36 minutes.
18	The lunar phase cycle lasts about 29.5 days. Find the time from new moon to full moon in days, to one decimal place.	Answer: New moon to full moon is about half a cycle; 29.5 divided by 2 is 14.75, that is about 14.8 days.
19	A solar panel of area 2.0 m2 receives 800 W per square metre of sunlight and has an efficiency of 22%. Find its electrical output in W.	Answer: Input power is 2.0 times 800, that is 1600 W; output is 1600 times 0.22, that is 352 W.
20	Earth orbits the Sun once a year, yet Hong Kong has different day lengths in summer and winter. Explain the seasons using the tilt of Earth axis and its revolution.	Answer: Earth axis is tilted about 23.5 degrees to its orbital plane, so during one orbit the two hemispheres lean towards the Sun in turn; the angle of sunlight and the length of day change, which produces the seasons.

Section F: Experimental Design and Data Recording

The items below concern experimental design and data handling.

#	Question	Answer and marking notes
21	A student studies how temperature affects the rate of dissolving salt: equal masses of salt are added to 100 cm3 of water at 20, 40 and 60 degrees C and the time to dissolve completely is recorded. State the independent variable, the dependent variable and two controlled variables.	Answer: The independent variable is water temperature; the dependent variable is the time to dissolve. Controlled variables include the mass of salt, the water volume of 100 cm3, the type of water and the stirring method.
22	The length of a pencil is measured three times as 2.4 cm, 2.6 cm and 2.5 cm. Find the mean and state the purpose of repeating a measurement.	Answer: The mean is 7.5 divided by 3, that is 2.5 cm. Repeating a measurement reduces random error and makes the result more reliable.
23	In a spring experiment a 2 N weight stretches the spring by 3.0 cm, and extension is proportional to force. Find the extension per newton in cm/N and the extension with an 8 N weight in cm.	Answer: Extension per newton is 3.0 divided by 2, that is 1.5 cm/N; at 8 N the extension is 8 times 1.5, that is 12 cm.
24	A measured mean is 2.5 cm while the accepted value is 2.4 cm. Find the percentage error to one decimal place.	Answer: Percentage error is 2.5 minus 2.4, divided by 2.4, times 100, that is 4.2%.

Find a tutor — free Tutor Registration →

A TutorZone practice paper; original questions and passages, not publisher material.