identify the true statement. choose one: a. soil consists of rock or sediment that has been modified over time. b. the organic material at the top of a soil is called the b-horizon. c. a vertical sequence of various soil layers is called the soil horizon.

True, the hottest stars show little evidence of hydrogen in their spectra because hydrogen is mostly ionized at the high temperatures found in these stars.

The hottest stars, also known as O-type stars, show little evidence of hydrogen in their spectra because hydrogen is mostly ionized at the high temperatures found in these stars. O-type stars have surface temperatures of around 30,000 kelvin, which is hot enough to ionize hydrogen atoms and strip them of their electrons. As a result, the spectral lines that are normally associated with neutral hydrogen atoms, such as the Balmer series, are very weak or even absent in the spectra of O-type stars. Instead, these stars show strong spectral lines associated with ionized elements, such as helium, nitrogen, oxygen, and silicon, which are produced by the high temperatures and intense radiation fields found in these stars.

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The correct answers for the statement ''the hottest stars show little evidence of hydrogen in their spectra because hydrogen is mostly ionized in the stars temperatures'' is True.

The hottest stars have such high temperatures that the majority of the hydrogen atoms in their atmospheres are ionized, meaning they have lost their electrons. When this happens, the hydrogen atoms no longer absorb or emit light at the same wavelengths as neutral hydrogen atoms.

As a result, there is little evidence of hydrogen in the spectra of these stars. Instead, other elements that are present in the stars, such as helium and carbon, produce the dominant spectral lines. This is why the spectra of hot stars look very different from those of cooler stars, which have more neutral hydrogen in their atmospheres.

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The answers are given as follows:

Environmental concerns can decrease demand for coal because there is a growing awareness of the negative impact of burning fossil fuels on the environment.

As a result, industries and individuals are seeking alternative sources of energy that are more sustainable and eco-friendly.

On the other hand, agricultural output tends to increase demand for coal as it is often used to power machinery and equipment for farming and harvesting crops. The demand for coal as a power source in agriculture can increase as the need for food production grows, especially in developing countries where agriculture is a vital industry.

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The rubbing of the North American Plate against the Pacific Plate causes earthquakes along the Pacific Coast of North America.

The North American Plate and the Pacific Plate are two tectonic plates that meet at a boundary called the Pacific Plate Boundary. This boundary extends along the western coast of North America, from Alaska down to California. The two plates are moving in different directions, with the Pacific Plate moving northwest and the North American Plate moving southwest. As a result, the North American Plate is being pushed against the Pacific Plate, causing a buildup of stress and tension at the boundary. Eventually, this stress is released in the form of earthquakes, as the plates suddenly slip past each other. The Pacific Coast of North America is particularly vulnerable to earthquakes because it lies along this plate boundary, and the region has experienced some of the most significant earthquakes in history, such as the 1906 San Francisco earthquake and the 1964 Alaska earthquake. Earthquakes along the Pacific Coast can be very destructive, causing damage to buildings and infrastructure, and posing a significant threat to human safety.

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The rubbing of the North American Plate against the Pacific Plate causes Earthquakes along the Pacific Coast of North America.

The rubbing of the North American Plate against the Pacific Plate is a result of plate tectonics, and it is responsible for causing a number of geologic events along the Pacific Coast of North America. The most notable of these events are earthquakes, which are the result of the two plates grinding against each other.

This movement also causes the melting of glaciers, as the friction creates heat which melts the ice. The strain of the plates pushing against each other is also responsible for the formation of the Rocky Mountains, which are caused by the uplift of the plates. This same force can also cause volcanoes to form, as molten rock is forced up from the mantle. In all, the rubbing of the two plates has had a major effect on the geology of the region, and it continues to shape the landscape even today.

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The water source that may be placed within strategic locations by some suburban and urban jurisdictions as a backup water supply system is: c. cisterns.

The water source that may be placed within strategic locations by some suburban and urban jurisdictions as a backup water supply system is C. Cisterns. Cisterns are containers designed for storing water, which can be placed underground or above ground, and are commonly used to collect rainwater for later use. In some jurisdictions, cisterns may be placed in strategic locations as a backup water supply system, especially in areas prone to droughts or water shortages. Ground reservoirs, private water storage tanks, and swimming pools may also be used for storing water, but they are typically not used as backup water supply systems in suburban or urban areas.

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