Group A: Objective Questions (15 × 1 = 15 marks)
1. Choose the correct answer:
1️⃣ The unit of force is:
a) Joule b) Newton c) Watt d) Pascal
✅ Answer: b) Newton
2️⃣ The process of changing solid directly into gas is called:
a) Evaporation b) Condensation c) Sublimation d) Fusion
✅ Answer: c) Sublimation
3️⃣ Which metal is used in making electric wires?
a) Iron b) Silver c) Copper d) Zinc
✅ Answer: c) Copper
4️⃣ Which part of a plant performs photosynthesis?
✅ Answer: Leaf
5️⃣ The energy produced from nucleus of atom is called ______ energy.
✅ Answer: Nuclear energy
6️⃣ Which gas is produced during photosynthesis?
✅ Answer: Oxygen
7️⃣ The chemical symbol of sodium is ______.
✅ Answer: Na
8️⃣ The lens which is thicker at the center than at the edges is called ______.
✅ Answer: Convex lens
9️⃣ The process of preventing rusting of iron is called ______.
✅ Answer: Galvanization
10️⃣ The nearest planet to the Sun is ______.
✅ Answer: Mercury
Group B: Short Answer Questions (8 × 5 = 40 marks)
1. State Newton’s three laws of motion.
✅ Answer:
1️⃣ First Law – A body remains at rest or in uniform motion unless acted upon by an external force.
2️⃣ Second Law – Force = mass × acceleration (F = ma).
3️⃣ Third Law – For every action, there is an equal and opposite reaction.
2. Write the differences between AC and DC current.
| AC (Alternating Current) | DC (Direct Current) |
|---|---|
| Changes direction periodically | Flows in one direction only |
| Produced by alternators | Produced by batteries |
| Can be transmitted over long distance easily | Difficult to transmit far |
| Used in household supply | Used in electronic devices |
3. Define reflection and refraction with one example each.
✅ Answer:
- Reflection: The bouncing back of light from a surface.
Example: Image formation in a mirror. - Refraction: The bending of light as it passes from one medium to another.
Example: A pencil appearing bent in water.
4. Write down the differences between physical and chemical changes.
| Physical Change | Chemical Change |
|---|---|
| No new substance formed | New substance formed |
| Usually reversible | Irreversible |
| Only physical properties change | Both physical and chemical properties change |
| Example: Ice melting | Example: Iron rusting |
5. What is the importance of water in our daily life? Mention any four points.
✅ Answer:
- Used for drinking and cooking.
- Needed for irrigation in agriculture.
- Used in industries and power generation.
- Maintains body temperature and ecosystem balance.
6. What is greenhouse effect? How does it cause global warming?
✅ Answer:
Greenhouse effect is the trapping of heat in Earth’s atmosphere due to gases like CO₂, methane, and water vapor.
These gases absorb heat energy from sunlight and prevent it from escaping, raising the Earth’s average temperature — known as global warming.
7. Define acid and base with one example each.
✅ Answer:
- Acid: Substance that gives hydrogen ions (H⁺) in water. Example: HCl
- Base: Substance that gives hydroxide ions (OH⁻) in water. Example: NaOH
8. Write two advantages and disadvantages of nuclear energy.
✅ Answer:
Advantages:
- Produces large amount of energy from small mass.
- No greenhouse gas emission during operation.
Disadvantages:
- Radioactive waste disposal is difficult.
- High risk of radiation and accidents.
Group C: Long Answer Questions (2 × 10 = 20 marks)
1. Explain the structure and working principle of a simple electric motor with a labeled diagram.
✅ Answer (summary):
A simple motor converts electrical energy into mechanical energy.
It consists of a rectangular coil placed between poles of a magnet.
When current passes through the coil, it experiences a magnetic force that rotates it — due to Fleming’s left-hand rule.
A split-ring commutator reverses current direction each half turn, ensuring continuous rotation.
(Diagram suggestion: show magnet poles, coil, brushes, split ring, battery)
2. Describe the structure and function of the human heart.
✅ Answer:
The heart is a muscular organ with four chambers — two atria (upper) and two ventricles (lower).
- The right side pumps deoxygenated blood to the lungs.
- The left side pumps oxygenated blood to the body.
Valves prevent backflow of blood.
The rhythmic contraction (heartbeat) maintains continuous blood circulation.
Normal heart rate = ~72 beats per minute.
