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Primary 6 PSLE Science Weighted Assessment 2 (Term 3) Paper 1
Free P6 PSLE Science WA2 Paper 1, Exam version, with questions, answers, and PSLE-focused practice for Singapore students.
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TuitionGoWhere P6 Science - WA2 Version 3 2026 ANSWER KEY
Assessment: Weighted Assessment 2 (WA2) - Version 3
Total Marks: 100 marks
SECTION A: Multiple Choice Questions - ANSWERS (56 marks)
- (B) Chemical → Electrical → Sound - Battery provides chemical energy converted to electricity then sound.
- (B) 3V - Series circuits divide voltage equally among components.
- (D) Chemical change that is irreversible - Protein denaturation creates new substances.
- (B) Kinetic energy to electrical energy - Turbine movement generates electricity.
- (C) Carbon dioxide - Not a primary factor in rusting process.
- (B) Parallel only - Allows independent operation of appliances.
- (C) Chemical energy - Energy stored in molecular bonds of fuel.
- (C) Rubber - Excellent electrical insulator for safety.
- (B) Useful energy output to total energy input - Definition of efficiency.
- (B) Chemical change only - Chemical reaction forms new compounds.
- (C) Ohm - SI unit for electrical resistance (Ω).
- (D) Through transparent materials and vacuum - Light doesn't need matter to travel.
- (B) Chromium - Forms protective oxide layer preventing rust.
- (B) Maximum potential energy - Highest position means maximum PE.
- (D) Longer length - More length means more resistance.
- (B) Earth's internal heat - Geothermal energy from Earth's core.
- (B) Physical change - Direct solid to gas transition, no new substances.
- (B) Electrical energy to kinetic energy - Motors convert electricity to motion.
- (C) Safety protection - Earth wire prevents electric shock.
- (D) Elastic potential energy - Energy stored in compressed elastic materials.
- (B) Mixing sand and water - Physical mixture easily separated.
- (B) From negative to positive - Electron flow direction.
- (B) Chemical energy from living materials - Energy from organic matter.
- (B) All bulbs stop working - Series circuit failure affects entire circuit.
- (C) Movement of fluids - Heat transfer through fluid circulation.
- (B) A physical change - Separation process, no new substances formed.
- (C) Water turbines - Ocean movement drives turbines for electricity.
- (B) Two separate insulating materials - Double protection from electrical shock.
SECTION B: Open-Ended Questions - ANSWERS (44 marks)
Question 1 (15 marks) - Energy Efficiency Investigation
(a) Energy efficiency calculations: (6 marks - 2 marks each)
LED efficiency: 80% (1 mark) Working: (8 ÷ 10) × 100 = 80% (1 mark)
CFL efficiency: 60% (1 mark)
Working: (12 ÷ 20) × 100 = 60% (1 mark)
Incandescent efficiency: 10% (1 mark) Working: (10 ÷ 100) × 100 = 10% (1 mark)
(b) Most efficient bulb: (2 marks) Sample answer: LED bulbs are most energy efficient at 80%. They convert the highest percentage of electrical energy into useful light energy with the least waste as heat.
(c) Why incandescent bulbs produce heat: (2 marks) Sample answer: Incandescent bulbs work by heating a wire filament until it glows. Most energy (90%) is converted to heat, with only a small amount producing light.
(d) LED environmental benefits: (2 marks) Sample answer: LED bulbs use less electricity, reducing power plant emissions. They also last longer, reducing waste and manufacturing demand.
(e) Wasted energy calculation: (2 marks) Working: 100J/s input - 10J/s useful output = 90J/s wasted (1 mark) Wasted energy: 90 J/s (1 mark)
(f) Energy waste reduction: (1 mark) Sample answers: Use LED bulbs, turn off lights when not needed, use natural light when possible
Question 2 (15 marks) - Circuit Design
(a) Series circuit diagram: (3 marks) Single loop showing battery, 4 bulbs connected in sequence, and switch
- 1 mark for correct battery symbol
- 1 mark for 4 bulbs in single path
- 1 mark for proper connections and switch
(b) Series voltage calculation: (2 marks) Voltage per bulb: 3 V (1 mark) Calculation: 12V ÷ 4 bulbs = 3V per bulb (1 mark)
(c) Parallel circuit diagram: (3 marks) Battery connected to 4 separate branches, each containing one bulb
- 1 mark for correct battery symbol
- 1 mark for 4 separate branches
- 1 mark for proper parallel connections
(d) Parallel voltage: (1 mark) Voltage per bulb: 12 V
(e) Brighter circuit explanation: (3 marks) Arrangement: Parallel circuit (1 mark) Explanation: Each bulb receives the full 12V in parallel, compared to only 3V each in series. Higher voltage means brighter bulbs. (2 marks)
(f) Effect of broken bulb: (2 marks) Series circuit: All bulbs stop working - circuit is broken (1 mark) Parallel circuit: Other 3 bulbs continue working normally (1 mark)
(g) Why homes use parallel wiring: (1 mark) Sample answer: Devices can be controlled independently and work at full voltage
Question 3 (14 marks) - Change Classification
(a) Scenario classification: (6 marks - 1 mark each)
| Scenario | Type of Change | Energy Change |
|---|---|---|
| A | Physical | Heat absorbed |
| B | Chemical | Chemical → Heat + Light |
| C | Chemical | Chemical → Electrical |
| D | Physical | Heat absorbed |
| E | Chemical | Light → Chemical |
| F | Chemical | Chemical → Heat + Kinetic |
(b) Wood burning energy transformation: (3 marks) Sample answer: Chemical energy stored in wood molecules is released through combustion. This chemical energy converts to heat energy (warming surroundings) and light energy (flames). Some energy may also produce sound and kinetic energy from gas expansion.
- 1 mark for chemical energy release
- 1 mark for heat energy production
- 1 mark for light energy production
(c) Importance of photosynthesis: (2 marks) Sample answer: Photosynthesis converts light energy into chemical energy (glucose), providing food for plants and oxygen for other organisms. It forms the base of most food chains and energy cycles.
(d) Energy storage scenario: (2 marks) Scenario: E (photosynthesis) (1 mark) Explanation: Light energy is stored as chemical energy in glucose molecules for later use (1 mark)
(e) Reversing melting without artificial cooling: (1 mark) Sample answer: Move to a colder location/shade, wait for nighttime when temperature drops
MARKING GUIDELINES:
Assessment Focus:
- Energy efficiency calculations and comparisons
- Circuit design and analysis
- Change classification with energy considerations
- Real-world applications of scientific principles
Grade Boundaries:
- A: 85-100 marks (Strong integration of energy and electrical concepts)
- B: 75-84 marks (Good understanding with minor gaps)
- C: 65-74 marks (Basic competency, some reinforcement needed)
- D: 50-64 marks (Significant conceptual gaps)
- Below 50 marks: Requires comprehensive review
Key Skills Demonstrated:
- Mathematical calculations in scientific contexts
- Circuit analysis and practical applications
- Energy transformation understanding
- Classification and reasoning skills
- Environmental awareness connections