Top 100 MCQs for PSLE Science 2026 — Most Important Questions

Topic	Avg. MCQs in Exam	Frequency	Focus
⚡ Forces & Simple Machines	4–6	Very High	🔥 Must master
💡 Electrical Systems	4–5	Very High	🔥 Must master
🦁 Animals & Body Systems	4–5	Very High	🔥 Must master
🧪 Matter & Materials	3–4	High	📌 Important
🌐 Food Chains & Webs	3–4	High	📌 Important
🌿 Photosynthesis & Plants	3–4	High	📌 Important
🌸 Reproduction	2–3	Medium	📝 Study well
💧 Water Cycle	2–3	Medium	📝 Study well
🧲 Magnets	1–2	Lower	✅ Know basics
🔆 Light & Shadows	1–2	Lower	✅ Know basics

🎯 Practice Questions

100 Most Important PSLE Science MCQs

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⚡

Forces & Simple Machines

Questions 1–12 · High-frequency · Must master

12 MCQs

Q1Easy

Which of the following is a non-contact force?

💡 Explanation

Gravitational force acts at a distance — no physical contact is needed. The three non-contact forces in PSLE are: Gravitational, Magnetic, and Electrostatic. Friction, push, and pull all require physical contact.

Q2Easy

A book is resting on a table. Which two forces are acting on the book?

💡 Explanation

A stationary book on a table is in equilibrium — two forces act on it: Gravitational force pulling it downward, and the Normal force (or contact force/reaction force) from the table pushing it upward. These two forces are equal in size and opposite in direction.

Q3Medium

A spring stretches 3 cm when a 200g mass is hung on it. How far will it stretch with a 600g mass?

💡 Explanation

Elastic spring force is proportional to the load. 200g → 3cm means each 200g = 3cm stretch. 600g = 3 × 200g, so stretch = 3 × 3cm = 9cm. This tests Hooke's Law — the extension is proportional to the force applied.

Q4Medium

Which situation shows friction being USEFUL?

💡 Explanation

Car brakes use friction between brake pads and wheels to slow the car — this is a useful application. Other examples of useful friction: grip of shoes on floor, writing with a pencil, sandpaper smoothing wood. Friction is harmful when it causes wear, heat, or energy loss.

💡

Electrical Systems

Questions 13–24 · High-frequency · Must master

12 MCQs

Q13Easy

In a parallel circuit with two bulbs, one bulb is removed. What happens to the other bulb?

💡 Explanation

In a parallel circuit, each branch has its own independent path to the battery. Removing one bulb does not affect the other branch — the remaining bulb stays lit at the same brightness. This is why home lighting uses parallel circuits.

Q14Medium

Which material is an electrical conductor?

💡 Explanation

Copper is an excellent electrical conductor — it allows current to flow through it easily. This is why wires are made of copper. Rubber, plastic, and wood are insulators that resist the flow of electricity. Remember: all metals are conductors (except a few exceptions not in PSLE).

Q15Hard

Two identical bulbs are connected in series with a battery. A third identical bulb is then added in series. What happens to the brightness of the original two bulbs?

💡 Explanation

In a series circuit, adding more bulbs increases resistance in the circuit, which reduces the total current flowing. Less current = less brightness for all bulbs. With 3 bulbs in series, each bulb gets less current than with 2 bulbs. All three burn at equal (but reduced) brightness.

🌿

Plants & Photosynthesis

Questions 25–36 · High-frequency

12 MCQs

Q25Easy

What are the THREE conditions necessary for photosynthesis to occur?

💡 Explanation

The PSLE formula: Water + Carbon Dioxide + Light → Glucose + Oxygen. The three CONDITIONS needed are water, carbon dioxide (raw materials), and light (energy source). Oxygen and glucose are the PRODUCTS — not conditions. Chlorophyll in leaves captures the light energy.

Q26Medium

A leaf was boiled in ethanol and then tested with iodine solution. What does a blue-black colour indicate?

💡 Explanation

Iodine solution turns blue-black in the presence of starch. In photosynthesis, glucose produced is converted to starch for storage. The leaf is boiled in ethanol first to remove the green chlorophyll pigment, making the colour change visible. Brown/orange = no starch present.

🦁

Animals & Body Systems

Questions 37–50 · Very High-frequency

14 MCQs

Q37Easy

Which organ produces digestive juices that break down all three types of food (carbohydrates, proteins, and fats)?

💡 Explanation

The pancreas produces digestive juices (enzymes) that can break down all three food types: carbohydrates → sugars, proteins → amino acids, fats → fatty acids and glycerol. The stomach only breaks down proteins. The liver produces bile to emulsify fats (not digest them).

Q38Medium

Where does gas exchange (oxygen and carbon dioxide) occur in the human body?

💡 Explanation

Alveoli (tiny air sacs in the lungs) are where gas exchange takes place. Oxygen from inhaled air passes into the blood, and carbon dioxide from the blood passes into the air sacs to be exhaled. The alveoli have thin walls and a rich blood supply for efficient gas exchange.

🧪

Matter & Materials

Questions 51–62 · High-frequency

12 MCQs

Q51Easy

Which method is best for separating a mixture of sand and water?

💡 Explanation

Filtration separates an insoluble solid (sand) from a liquid (water) using filter paper. Sand is too large to pass through the tiny holes in filter paper and remains as residue. Use evaporation to separate a dissolved solid (like salt) from water.

Q52Medium

Which property does NOT change when a substance changes state (e.g., from liquid to gas)?

💡 Explanation

Mass is conserved during changes of state — the amount of matter stays the same. When liquid water evaporates to become water vapour, the total mass remains the same; the molecules just spread out more. Volume, shape, and density all change during state changes.

🌐

Food Chains & Food Webs

Questions 63–74 · High-frequency

12 MCQs

Q63Easy

In any food chain, which organism is ALWAYS first?

💡 Explanation

All food chains start with a producer — a green plant (or organism that can make its own food through photosynthesis). Producers capture the sun's energy and make it available to all other organisms in the food chain. Without producers, no food chain can exist.

Q64Hard

In a food web, if the population of frogs suddenly decreases, which of the following is MOST LIKELY to happen?

💡 Explanation

If frogs decrease, their prey (grasshoppers) will have fewer predators — so grasshopper population will increase. Meanwhile, snakes (which eat frogs) will have less food, so snake population may decrease. This is the classic predator-prey interdependence question.

🎯

Questions 75–100

Covering: Reproduction, Water Cycle, Magnets, Light & Shadows, Environment, and Mixed Review

🌸 Reproduction Q&A 💧 Water Cycle Q&A 🧲 Magnets Q&A 🔭 All Topics Hub

Top 100 MCQs for PSLE Science

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100 Most Important PSLE Science MCQs

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