Geology 101 Test 2

In the mineral calcite (CaCO3), each oxygen atom carries a charge of -2. Since there are three oxygen atoms, the total negative charge from oxygen is -6. To balance this charge and maintain the overall neutral charge of the molecule, the carbon atom must have a valence or charge of +4, making the correct answer +4.

The correct answer is the false statement that humus accumulates in and is most abundant in the C horizon. In reality, the C horizon is usually composed of weathered parent material with minimal organic content, while the A horizon is typically the topsoil layer where organic matter and roots are most concentrated. The B horizon, on the other hand, is rich in minerals leached from the A horizon, making it distinct from the other horizons.

Sheet silicates are minerals that are composed of continuous layers of silicate tetrahedra, resulting in a sheet-like structure. Biotite is a common sheet silicate mineral, known for its black or dark brown color.

Pyroxene is classified as a single-chain silicate due to its structure and chemical composition.

Framework silicates are minerals that have a three-dimensional structure of silicon-oxygen tetrahedra linked together. Potassium Feldspar, also known as K-Spar, is an example of a 3-D framework silicate mineral.

Amphibole is a mineral group that belongs to the double-chain silicate category, known for its elongated crystal structure. Quartz, Feldspar, and Mica are all different types of mineral groups that do not fall under the double-chain silicate classification.

Composite strata volcanoes are known for their explosive eruptions due to the buildup of viscous magma from subduction zones, leading to the formation of alternating layers of ash, lava, and volcanic rocks.

During partial melting of silicates, the less silica-rich components tend to melt first, leaving behind a residue that is more silica-rich compared to the original parent material.

Shiprock is a well-known rock formation in New Mexico that was formed by the erosion of a volcanic pipe and radiating dikes, not by any of the other geological processes mentioned in the incorrect answers.

Limestone is a sedimentary rock composed primarily of calcium carbonate, making it more vulnerable to dissolution by acid rain compared to other types of rocks such as granite, marble, and basalt.

Isotopes are forms of an element that have different numbers of neutrons while maintaining the same number of protons, leading to variation in atomic mass but not in chemical properties.

Granite is primarily composed of Na-rich plagioclase, K-Spar (orthoclase), and quartz. The incorrect answers listed do not accurately represent the dominant minerals found in Granite.

The olivine solid solution series involves the substitution of Mg+2 for Fe+2 in varying ratios, resulting in a continuous range of compositions.

On the Mohs scale of Hardness, Topaz has a hardness of 8 while Quartz has a hardness of 7. Therefore, Topaz can scratch Quartz.

Amphiboles are mineral groups that have a double chain silicate structure with water in the form of OH. This unique structure gives amphiboles their characteristic properties.

An atom and an ion of the same element must have the same number of protons because protons determine the element's identity. Neutrons can vary, electrons can vary for ions, and valence electrons are specific to the ion's electronic configuration.

Ferromagnesian silicates are commonly dark-colored minerals that contain iron and magnesium, giving them their distinctive black to dark-green appearance.

Partial melting of a rock can result in the formation of different types of igneous rocks depending on the composition of the parent rock and the conditions of the melting process. Therefore, it is not accurate to say that a specific type of rock can never be produced through partial melting of a different type of rock.

Hydrosis of orthoclase feldspar results in the breakdown of the mineral into clay minerals, silica, and potassium, which can be dissolved in the soil water. Weathering of limestone, erosion of topsoil, and decomposition of organic matter do not directly lead to the specific products mentioned in the question.

Before the 1991 Pinatubo eruption, scientists did observe magma in a lava dome inside the crater, indicating the buildup of pressure below the surface.

In a silicate tetrahedron, the Ion at the center is surrounded by 4 Oxygen ions, forming a tetrahedral structure.

Carbonic acid is formed when water reacts with CO2 in the atmosphere through a chemical reaction.

Magma rises towards the earth's surface primarily because rocks generally become less dense than the rocks around them due to the increase in temperature and pressure as it moves closer to the surface.

Highly explosive eruptions are typically associated with the buildup of pressure from viscous magma and gas within stratovolcanoes or large composite cones. The subduction of oceanic lithosphere adds water to the magma, further increasing the explosiveness of the eruption.

High viscosity makes the magma more resistant to flow, trapping the gas bubbles within it. This leads to a build-up of pressure, increasing the explosive potential of the magma body beneath a volcano.

The 1943 eruption of Paricutin in Mexico was known for the formation of a cinder cone and the eruption of basaltic lava, not pyroclastic flows and rhyolitic lava, lava domes and andesitic lava, or shield volcano formation and dacitic lava.

Aphanitic texture refers to a fine-grained rock where the mineral grains are too small to be seen without magnification.

Deep mantle hot spots are locations where plumes of hot material rise from deep within the Earth's mantle, generating volcanic activity. The volcanoes of Hawaii and the Quaternary activity in Yellowstone National Park are classic examples of regions associated with deep mantle hot spots, while the Great Barrier Reef, Amazon Rainforest, and Sahara Desert are not typically associated with this geological phenomenon.

Clays are composed of layer silicates, which have a sheet-like structure where the silicon and oxygen atoms are arranged in sheets, giving clays their unique properties.

Minerals are naturally occurring solid substances with a definite chemical composition and structure. They cannot exist in a gas or liquid state, like a gas or plasma, or be organic material.