Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
The correct answer is D. How national borders in a region change over time.
Explanation:
The main purpose of maps is to show geographical features including natural physical features such as mountains or rivers, and political features that refer to the use of land by humans and the divisions created by them. Due to this, through maps, it is possible to visually show cities, states, regions countries, etc. In this context, a series of maps can be used to show the evolution or change of national borders because this is part of political features. Also, other aspects such as policies, beliefs, or economic events are not geographical and due to this cannot be depicted through maps.
Option 3. The sentence that best summarizes the excerpt that we have here is Everyone sits by the fire, with Mother in a large chair. Meg, Amy, and Beth all sit on the chair with Mother, but Jo leans on the back of the chair away from everyone else so no one can see her.
<h3>What is the summary of the excerpt?</h3>
The summary is from the way that the family is organized at the time period. They were said to have arranged themselves in a particular way. The way that Jo sat was so that no one in her family would see her.
The idea was so that they do not see her if she gets too emotional which may cause her to shed a tear or be unhappy.
The summary is described as the straight to the point way that excerpts use to describe events by using only basic ideas.
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Answer:
Una condición podría deberse al clima, los impuestos o los vecinos. Espero que esto haya ayudado.
Explanation:
