Science 4 · Unit 4: Earth and its habitats · Cambridge Primary Science Stage 4

Questions

1. 1. Which word completes the sentence? The ... structure of the Earth describes what is below the surface.

   • internal
   • external
   Check

2. 2. Is the Earth's crust thinner or thicker below the oceans than below the land?

   • thinner
   • thicker
   Check

3. 3. Is the outer core of the Earth solid or liquid?

   • solid
   • liquid
   Check

4. 4. What is the Earth's core made of?

   • metals
   • magma
   • water
   • sand
   Check

5. 5. What is the mantle made of?

   • magma
   • lava
   • metals
   • ice
   Check

6. 6. Which is the thinnest layer of the Earth?

   • the inner core
   • the outer core
   • the mantle
   • the crust
   Check

7. 7. What happens to the temperature as you get closer to the centre of the Earth?

   • It increases.
   • It decreases.
   • It stays the same.
   Check

8. 8. Which is the thickest layer of the Earth?

   • the mantle
   • the crust
   • the outer core
   • the inner core
   Check

9. 9. Is the inner core of the Earth solid or liquid?

   • solid
   • liquid
   Check

10. 10. Is magma a solid or a liquid?

    • a solid
    • a liquid
    Check

11. 11. What are the four layers of the Earth, from the outside in?

    • inner core, outer core, mantle, crust
    • crust, mantle, outer core, inner core
    • mantle, crust, inner core, outer core
    • crust, outer core, mantle, inner core
    Check

12. 12. Which layer of the Earth is solid rock?

    • the outer core
    • the crust
    • the inner core
    • the mantle
    Check

13. 13. How deep is the deepest hole ever drilled into the Earth's crust?

    • about 1 km
    • about 12 km
    • about 6400 km
    • about 120 km
    Check

14. 14. Why could the scientists not drill a deeper hole?

    • It was too hot at the bottom, about 180 °C.
    • They reached the core.
    • The hole filled with water.
    • The drill hit the outer core.
    Check

15. 15. About how far is it from the surface to the centre of the Earth?

    • about 640 000 km
    • about 12 km
    • about 180 km
    • about 6400 km
    Check

16. 16. How did scientists find out that the outer core is liquid and the inner core is solid?

    • They studied earthquake waves travelling through the Earth.
    • They drilled a hole to the core.
    • They looked inside a volcano.
    • They took photos from space.
    Check

17. 17. Why can earthquake waves tell scientists what is inside the Earth?

    • The waves carry pieces of rock back to the surface.
    • The waves only travel through liquids.
    • The speed of the waves changes with the hardness of the material they pass through.
    • The waves change colour in each layer.
    Check