How Earth formed and separated into layers

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   Earth, average (NASA), 5,514; crust rock, about 3,000. NASA gives Earth's average density as 5,514 kg/m³, while crust rock is near 3,000 kg/m³. What does this show, by Bo's reading?

   • Earth is the same density throughout
   • The inside must be lighter than the crust, since it is so hot
   • Earth's crust is mostly iron
   • Earth's inside must be much denser than its crust
2. 2.

   A mixture of oil, water and sand is shaken and left to settle. How is this like early Earth, by Esme's reading?

   • Densest sinks, lightest floats, as iron sank and rock rose
   • Layers appear without any settling
   • Shaking makes the layers, as earthquakes did
   • The lightest part sinks, as the crust did
3. 3.

   Cutaway with blobs of iron in molten rock. Molten iron is denser than molten rock. In a partly molten young Earth, which way would it move, by Jun's reading?

   • It rises to the surface
   • It sinks toward the center
   • It stays where it is
   • It escapes into space through the crust

4. Read this first

   Table, Earth's layers (USGS), with columns Layer, Thickness, State

   Crust, about 5 km (oceans) to 30 km (continents), solid, brittle; mantle, about 2,900 km, hot, semi-solid rock; outer core, about 2,200 km, liquid iron-nickel; inner core, about 1,250 km, solid iron-nickel.

5. 4.

   Using the USGS table, about how far is it from the surface to the top of the core under a continent, by Kira's math?

   • About 2,200 km
   • About 5,100 km
   • About 2,930 km
   • About 30 km
6. 5.

   Using the table, about how thick is the whole core (outer plus inner), by Luz's math?

   • About 1,250 km
   • About 950 km
   • About 3,450 km
   • About 6,350 km
7. 6.

   Earth is about 12,750 km wide (USGS). A 30 km continental crust is what fraction of that, by Milo's math?

   • About 0.24%
   • About 50%
   • About 2.4%
   • About 24%
8. 7.

   Why does Earth have a magnetic field while the Moon has almost none today, by Noah's reading?

   • Earth has a large, moving liquid outer core
   • Earth's crust is made of strongly magnetic rock
   • Earth's solid inner core spins on its own
   • The Moon's surface blocks its field
9. 8.

   Cutaway of the inner core labeled 5,400 °C. NASA gives the inner core a radius of about 1,221 km and a temperature as high as 5,400 °C (9,800 °F). Why is it solid, by Ren's reading?

   • Huge pressure keeps it solid despite the heat
   • It is liquid, like the outer core
   • It is cold, below freezing
   • It is made of light rock
10. 9.

    Earth is about 4.54 billion years old. On a 4.54 m timeline (1 m per billion years), how far from the start is a mark for 4.0 billion years ago, by Tala's math?

    • About 4.0 m
    • About 54 m
    • About 0.54 m
    • About 0.54 mm

11. Table, Earth's layers (USGS), with columns Layer, Thickness, State

    Crust, about 5 km (oceans) to 30 km (continents), solid, brittle; mantle, about 2,900 km, hot, semi-solid rock; outer core, about 2,200 km, liquid iron-nickel; inner core, about 1,250 km, solid iron-nickel.

12. 10.

    Which statement about the lithosphere is right, by Ari's reading (USGS)?

    • It is the inner core's surface
    • It is the rigid crust plus the upper mantle, at least 80 km thick
    • It is the crust alone, 2,900 km thick
    • It is the liquid outer core