S2 Integrated Science Practice Paper | Investigation Skills, Particles, Cells, Forces, Energy And Heat, Earth And Environment (with Answers)

S2 Integrated Science Practice Paper | Investigation Skills, Particles, Cells, Forces, Energy and Heat, Earth and Environment (with answers)

2026-11-15

Integrated Science · S2

S2 Integrated Science paper: 6 questions, 24 parts, 100 marks, 60 minutes, covering particles, cells, forces, energy and earth, with original answers and a mark scheme PDF.

Paper details　S2 Integrated Science Practice Paper | Investigation Skills, Particles, Cells, Forces, Energy and Heat, Earth and Environment (with answers)

Scientific Investigation and Practical Skills

Read the situations below and answer each part.

#	Question	Answer and marking notes
1	A student uses the same measuring cylinder four times for the same sample of water and records 24.6 cm³, 24.4 cm³, 24.8 cm³ and 24.2 cm³. Find the mean of the four readings.	Answer: 24.5 cm³. (24.6 + 24.4 + 24.8 + 24.2 = 98.0; 98.0 ÷ 4 = 24.5 cm³)
2	The true volume of the water is 25.0 cm³. Calculate the percentage error using the mean value, correct to one decimal place.	Answer: 2.0%. (error = \|24.5 − 25.0\| = 0.5 cm³; 0.5 ÷ 25.0 × 100% = 2.0%)
3	A student studies how water temperature affects evaporation: four cups of the same amount of water are kept at 20 °C, 30 °C, 40 °C and 50 °C and the mass lost by each cup is measured after two hours. State the independent and dependent variables.	Answer: independent variable is the water temperature; dependent variable is the mass lost after two hours. The amount of water, the shape of the cup and the humidity must be kept constant.
4	State two safety rules that must be followed when heating a liquid in a test tube.	Answer: the mouth of the test tube must not point towards yourself or others; use a test tube holder and move the tube through the liquid, never heat one spot at the bottom only.

Matter and Particles

The following parts are about classifying matter and the particle model.

#	Question	Answer and marking notes
5	Classify oxygen (O2), carbon dioxide (CO2) and salt solution as element, compound or mixture, giving one reason for each.	Answer: oxygen is an element because it contains only one kind of atom; carbon dioxide is a compound because two elements are chemically combined in a fixed ratio; salt solution is a mixture because salt and water are mixed in a variable ratio.
6	A drop of red ink is put into a beaker of clear water. After a few minutes the whole beaker looks pale red. Explain this with the particle model.	Answer: ink particles and water particles move randomly and there is empty space between them, so the ink particles spread out and become evenly mixed with the water. This is diffusion.
7	A piece of metal has a mass of 54 g and a volume of 20 cm³. Find its density.	Answer: 2.7 g/cm³. (54 g ÷ 20 cm³ = 2.7 g/cm³)
8	Name the changes of state: solid to liquid; liquid to gas.	Answer: solid to liquid is melting; liquid to gas is boiling or evaporation.

Cells and Life

The following parts are about cell structure and photosynthesis.

#	Question	Answer and marking notes
9	State one main function each of the cell wall, the chloroplast and the nucleus, and state how plant cells differ from animal cells in the cell wall.	Answer: the cell wall supports and protects the cell; the chloroplast carries out photosynthesis to make food; the nucleus controls cell activities and stores genetic material. Plant cells have a cell wall, animal cells do not.
10	Write the word equation for photosynthesis and state the energy source.	Answer: carbon dioxide + water → glucose + oxygen; the energy source is light, absorbed by chlorophyll.
11	The eyepiece of a microscope magnifies 10 times and the objective magnifies 40 times. Find the total magnification.	Answer: 400 times. (10 × 40 = 400)
12	At that magnification the image of a cell is 20 mm long. Find the actual length of the cell in micrometres (µm).	Answer: 0.05 mm, that is 50 µm. (20 mm ÷ 400 = 0.05 mm; 0.05 mm = 50 µm)

Force and Motion

The following parts are about speed, gravity and friction.

#	Question	Answer and marking notes
13	A student runs 120 m at a steady speed in 15 s. Find the average speed and state the acceleration when the speed is steady.	Answer: average speed 8.0 m/s; when the speed is steady the acceleration is 0 m/s².
14	A box of mass 2.5 kg rests on the Earth where the gravitational field strength is 10 N/kg. Find the weight of the box.	Answer: 25 N. (2.5 kg × 10 N/kg = 25 N)
15	A horizontal force of 30 N is applied to a stationary box and the box does not move; the friction on the box is 30 N. Find the net force on the box and explain why it stays at rest.	Answer: the net force is 0 N. The push and the friction are equal in size and opposite in direction, so they cancel out and the box stays at rest.
16	State two factors that affect sliding friction and give one everyday example for each.	Answer: first, the roughness of the surfaces: a rougher surface gives more friction, so a wet tiled floor makes slipping more likely. Second, the normal force (the weight of the object): a heavier object gives more friction, so an empty box is easier to push than a full one.

Energy and Heat

The following parts are about energy transfer, specific heat capacity and power.

#	Question	Answer and marking notes
17	A ball falls from a height. Describe the energy changes during the fall and explain why the ball becomes slightly warmer after it lands.	Answer: gravitational potential energy is changed into kinetic energy; when the ball hits the ground some kinetic energy changes into internal (thermal) energy, so the ball becomes slightly warmer.
18	Water of mass 0.5 kg is heated from 20 °C to 40 °C. The specific heat capacity of water is 4200 J/(kg·°C). Find the energy absorbed in kJ.	Answer: 42 kJ. (0.5 kg × 4200 J/(kg·°C) × 20 °C = 42000 J = 42 kJ)
19	If the heating in the previous part takes 60 s, find the average power of the heater.	Answer: 700 W. (42000 J ÷ 60 s = 700 W)
20	Name the three ways in which heat is transferred.	Answer: conduction, convection and radiation.

Earth and Environment

The following parts are about the water cycle, rocks and air.

#	Question	Answer and marking notes
21	Describe evaporation, condensation and precipitation in the water cycle and state the role of solar energy.	Answer: solar energy heats water on the surface so that it evaporates; the vapour rises, cools and condenses into tiny droplets forming clouds; the droplets grow and fall back as rain or snow. These three processes form the water cycle.
22	Name the three main groups of rocks and give one example of each.	Answer: igneous rocks (for example granite), sedimentary rocks (for example sandstone) and metamorphic rocks (for example marble).
23	Name two renewable energy sources and state one limitation of using each in Hong Kong.	Answer: solar energy, because Hong Kong is densely built with tall buildings so roof area for panels is limited; wind energy, because the average wind speed is low so output is unreliable.
24	Name the two most abundant gases in dry air with their approximate percentage by volume, and state which one is needed for burning.	Answer: nitrogen about 78%, oxygen about 21%; oxygen is needed for burning.

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