Igneous Rocks Quiz

What is the process of formation of igneous rocks?

• Erosion and deposition of sedimentary rocks

• Metamorphism of existing rocks

• Solidification or crystallization of molten magma or lava

• Volcanic eruption and cooling of lava

Answer explanation

Igneous rocks are formed through the process of solidification or crystallization of molten magma or lava. This process occurs when magma from beneath the Earth's surface cools and hardens. The other options, such as erosion and deposition, metamorphism, and volcanic eruption and cooling, are related to the formation of other types of rocks, not igneous rocks.

What are the two main types of igneous rocks based on their texture?

• granite and basalt

• intrusive and extrusive

• sedimentary and metamorphic

• volcanic and plutonic

Answer explanation

The two main types of igneous rocks based on their texture are intrusive and extrusive. Intrusive igneous rocks form from magma that cools slowly beneath the Earth's surface, resulting in large, visible crystals. Extrusive igneous rocks form from lava that cools quickly on the Earth's surface, resulting in small, barely visible crystals.

Which type of igneous rocks have a fine-grained texture?

• Extrusive igneous rocks

• Sedimentary rocks

• Metamorphic rocks

• Intrusive igneous rocks

Answer explanation

Extrusive igneous rocks have a fine-grained texture. This is because they cool and solidify quickly on the Earth's surface, which doesn't allow large crystals to form. In contrast, intrusive igneous rocks cool slowly beneath the surface, allowing large crystals to form. Therefore, sedimentary and metamorphic rocks are not the correct options as they are not types of igneous rocks.

Which type of igneous rocks have a coarse-grained texture?

• Sedimentary rocks

• Metamorphic rocks

• Intrusive igneous rocks

• Extrusive igneous rocks

Answer explanation

Intrusive igneous rocks have a coarse-grained texture because they form from magma that cools slowly beneath the Earth's surface. This slow cooling process allows for the growth of large mineral crystals, giving the rock its coarse-grained appearance. In contrast, extrusive igneous rocks cool quickly at the surface, resulting in a fine-grained texture, while sedimentary and metamorphic rocks are not formed from magma.

What is the mineral composition of igneous rocks primarily determined by?

• Cooling and solidification of magma or lava

• Biological processes

• Weathering and erosion

• Pressure and heat

Answer explanation

The mineral composition of igneous rocks is primarily determined by the cooling and solidification of magma or lava. This process allows minerals to crystallize and form the rock's structure. Biological processes, weathering and erosion, and pressure and heat do not directly determine the mineral composition of igneous rocks.

Tags

NGSS.MS-ESS2-1

Which type of igneous rocks are formed from lava that cools quickly on the Earth's surface?

• metamorphic rocks

• sedimentary rocks

• extrusive igneous rocks

• intrusive igneous rocks

Answer explanation

Extrusive igneous rocks are formed from lava that cools quickly on the Earth's surface. These rocks have a fine-grained texture due to the rapid cooling, which doesn't allow large crystals to form. In contrast, intrusive igneous rocks form from magma that cools slowly beneath the Earth's surface, resulting in a coarse-grained texture. Metamorphic and sedimentary rocks are not formed from lava or magma, but through different processes.

Which type of igneous rocks are formed from magma that cools slowly beneath the Earth's surface?

• Metamorphic rocks

• Extrusive igneous rocks

• Intrusive igneous rocks

• Sedimentary rocks

Answer explanation

Intrusive igneous rocks are formed when magma cools and solidifies beneath the Earth's surface. This process is slow due to the high pressure and lack of exposure to the atmosphere, allowing large crystals to form within the rock. This distinguishes them from extrusive igneous rocks, which cool quickly on the Earth's surface, and metamorphic and sedimentary rocks, which are formed through different geological processes.

Tags

NGSS.MS-ESS2-1

What is the most common extrusive igneous rock?

• basalt

• pumice

• granite

• obsidian

Answer explanation

The most common extrusive igneous rock is basalt. Extrusive igneous rocks form when magma reaches the Earth's surface a volcano and cools quickly. Basalt is the most common type because it is often produced in such conditions, unlike other options like pumice, granite, and obsidian which are less common.

What is the most common intrusive igneous rock?

• sandstone

• marble

• granite

• basalt

Answer explanation

The question asks about the most common intrusive igneous rock. Intrusive igneous rocks are formed from magma that cools and solidifies within the crust of the planet. Granite is the most common type of intrusive igneous rock, hence it is the correct answer. Other options like sandstone, marble, and basalt are not intrusive igneous rocks.

Which type of igneous rocks are usually light in color and have a high silica content?

• felsic rocks

• ultramafic rocks

• sedimentary rocks

• mafic rocks

Answer explanation

Felsic rocks are the correct choice because they are typically light in color and have a high silica content. These characteristics distinguish them from other types of igneous rocks, such as mafic and ultramafic rocks, which have lower silica content and darker colors. Sedimentary rocks, on the other hand, are not igneous rocks and are formed through different processes.