IGCSE Stage 8 Science Revision
Key Concepts & Quiz for Exam
Preparation
Materials and Cycles on Earth 🌍
• - **Element:** One type of atom
• - **Compound:** Two or more atoms
chemically combined
• - **Mixture:** Substances physically
combined
• - **Main Gases in Earth's Atmosphere:**
• - 78% Nitrogen (N₂), 21% Oxygen (O₂), 0.9%
Argon (Ar), 0.04% Carbon Dioxide (CO₂)
Light 💡
• - **Speed of Light:** 3.0 × 10⁸ m/s
• - **Why Objects Appear Different Colors:**
• - Objects absorb some wavelengths and
reflect others
• - **Total Internal Reflection:**
• - When light is completely reflected inside a
medium (used in fiber optics)
Diet and Growth 🍎
• - **Why We Need Carbohydrates:** Provides
energy for bodily functions
• - **Function of Iron in the Body:** Helps form
hemoglobin for oxygen transport
• - **Why Athletes Need Proteins:** Essential
for muscle growth and repair
Chemical Reactions ⚗️
• - **Metal + Acid Reaction:** Metal + Acid →
Salt + Hydrogen
• - **Physical vs. Chemical Change:**
• - Physical: No new substance, reversible (e.g.,
melting ice)
• - Chemical: New substance, irreversible (e.g.,
burning paper)
• - **Exothermic Reaction:** Releases heat
(e.g., combustion)
Magnetism 🧲
• - **How to Increase Electromagnet
Strength:**
• - Increase current, add more coils, use a soft
iron core
• - **Permanent Magnet vs. Electromagnet:**
• - Permanent: Always magnetic, cannot be
turned off
• - Electromagnet: Magnetism controlled by
electricity
Quiz Time! 🎯
• 1⃣ What is the main gas in Earth's atmosphere?
• 2⃣ What happens to light during total internal
reflection?
• 3️⃣ What is the function of hemoglobin in the
body?
• 4⃣ Write the reaction equation for a metal and
an acid.
• 5️⃣ How can you increase the strength of an
electromagnet?
Quiz Answers ✅
• 1⃣ 78% Nitrogen (N₂)
• 2⃣ Light is completely reflected inside a
medium
• 3️⃣ Hemoglobin carries oxygen in the blood
• 4⃣ Metal + Acid → Salt + Hydrogen
• 5️⃣ Increase current, add coils, use a soft iron
core