Answer:
A. Mass-extinction events are times in the Earth's history when few species evolve.
Explanation:
The extinction that occurred 65 million years ago wiped out some 50 percent of plants and animals. The event is so striking that it signals a major turning point in Earth's history, marking the end of the geologic period known as the Cretaceous and the beginning of the Tertiary period.
A wide range of animals and plants suddenly died out, from tiny marine organisms to large dinosaurs.
Species go extinct all the time. Scientists estimate that at least 99.9 percent of all species of plants and animals that ever lived are now extinct.
Answer:
A laser is created when the electrons in atoms in special glasses, crystals, or gases absorb energy from an electrical current or another laser and become “excited.” The excited electrons move from a lower-energy orbit to a higher-energy orbit around the atom's nucleus.
Answer:
Spherical concave mirrors
Explanation:
Like spherical convex mirrors, spherical concave mirrors have a focus. If the object is closer to the mirror than the focal point is, the image will be virtual, like we talked about before for the plane mirror and the convex mirror.
Concave mirrors, on the other hand, can have real images. If the object is further away from the mirror than the focal point, the image will be upside-down and real---meaning that the image appears on the same side of the mirror as the object.
The closer the object comes to the focal point (without passing it), the bigger the image will be.
You can try this yourself by looking into the concave side of a shiny spoon. If you look into the spoon while holding it at arm’s length, you’ll see an extremely magnified, upside-down image of your face. But as you bring the spoon closer to your eyes, the image will get bigger and bigger.
<em>- Hope this helps! <3</em>
Light through a vacuum. According to an official government sight, <em>nothing</em> travels faster than light through a vacuum.
The answer is <span>B. by increasing its mass. Hope it help!</span>
