Igneous rocks

What are igneous rocks?

• a. Rocks formed by the accumulation of sediments

• b. Rocks formed by extreme heat and pressure

• c. Rocks formed by the solidification of lava or magma

• d. Rocks formed by chemical reactions in water

Which factor determines whether an igneous rock is classified as plutonic or surface?

• a. The mineral composition

• b. The location where it solidifies

• c. The age of the rock

• d. The color of the rock

Why do plutonic igneous rocks have large crystals?

• a. Because they form under extreme pressure

• b. Because they form from specific minerals

• c. Because magma cools very slowly inside Earth's crust

• d. Because they are exposed to weathering

Which of these is NOT an example of a surface igneous rock?

• a. Basalt

• b. Pumice

• c. Granite

• d. Obsidian

What happens when lava cools quickly on Earth's surface?

• a. It forms rocks with large crystals

• b. It forms rocks with small crystals

• c. It doesn't form rocks at all

• d. It forms sedimentary rocks

What type of igneous rock is gabbro?

• a. Surface igneous rock

• b. Metamorphic rock

• c. Plutonic igneous rock

• d. Sedimentary rock

Where do plutonic igneous rocks form?

• a. In ocean waters

• b. Between cracks and layers of Earth's crust

• c. On Earth's surface

• d. In the atmosphere