Understanding Igneous Rocks

What is the primary difference between magma and lava?

• Magma is only found in volcanoes, while lava is found everywhere.

• Lava is cooler than magma.

• Magma is molten rock beneath the Earth's surface, while lava is magma that has erupted onto the surface.

• Magma is found on the Earth's surface, while lava is found beneath it.

Which type of igneous rock forms from magma that cools slowly beneath the Earth's surface?

• Intrusive igneous rock

• Sedimentary rock

• Extrusive igneous rock

• Metamorphic rock

Why do intrusive igneous rocks have larger crystals?

• They cool slowly, giving crystals more time to develop.

• They are formed from lava on the Earth's surface.

• They cool quickly, allowing crystals to grow larger.

• They are exposed to higher temperatures.

What characteristic is typical of extrusive igneous rocks?

• They have large, visible crystals.

• They are coarse-grained.

• They are fine-grained and may appear glassy.

• They form deep within the Earth.

Which of the following is the most common extrusive igneous rock on Earth?

• Dolorite

• Obsidian

• Basalt

• Granite