Free GED Science Earth and Space Science Practice Test

Question 1

Which layer of the Earth is the thinnest?

Accepted Answer

Crust

Answer

Earth's crust is the outermost and thinnest layer — ranging from about 5 km under oceans to 35-70 km under continents.

Question 2

What is the primary gas in Earth's atmosphere?

Accepted Answer

Nitrogen

Answer

Earth's atmosphere is approximately 78% nitrogen, 21% oxygen, and smaller amounts of other gases.

Question 3

Which type of rock forms when molten rock cools and solidifies?

Accepted Answer

Igneous

Answer

Igneous rock forms from the cooling and solidification of magma (underground) or lava (on the surface).

Question 4

What causes the seasons on Earth?

Accepted Answer

The tilt of Earth's axis as it orbits the Sun

Answer

Earth's seasons are caused by the 23.5° tilt of its axis. As Earth orbits the Sun, different hemispheres receive more direct sunlight at different times.

Question 5

What is the name of the supercontinent that existed approximately 300 million years ago?

Accepted Answer

Pangaea

Answer

Pangaea was the single supercontinent that existed about 300-200 million years ago before breaking apart into today's continents.

GED Practice Test

GED Practice Test

Free GED Science Earth and Space Science Practice Test