EXTRUSIVE IGNEOUS ROCK
When lava reaches the surface of the Earth through volcanoes or through great fissures the rocks that are formed from the lava cooling and hardening are called extrusive igneous rocks. Some of the more common types of extrusive igneous rocks are lava rocks, cinders, pumice, obsidian , and volcanic ash and dust.
Answer:
d) Chemical composition of its outer regions
Explanation:
Spectroscopy is the study of spectral lines, it's an important part of studying the chemistry that goes on in stars and interstellar clouds, spectral lines can give relevant information because every atom or molecule gives off light at a specific frequency, thus, astronomers can look for gas containing a particular atom or molecule by tuning the telescope to one of the gas's characteristic frequencies. Therefore, we can know the chemical composition or a star's outer regions analyzing the spectral lines.
Even though the spectral shape of a blackbody continuum depends on the temperature of the object an there's a relationship between an object’s temperature and the peak of its spectrum, we don't consider this answer as correct because we are not measuring spectral lines but the continuum.
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Answer: The two major geographic features provided on the east and west boundaries of piece of land are:
1. The land is "Louisiana Purchase".
2. The east boundary is "Mississippi".
3. The west boundary is "The Rockies".
Explanation: The Louisiana purchase is a piece of land of about 530,000 acres which was sold by France to the US President which was Thomas Jefferson in 1804.