<span>the most abundant type of rocks on earth are classified as - </span>a. igneous
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.
Russia
con 6.6 million de personas
The Republic of Texas extended up into the current state of Wyoming. The Red River and the Arkansas Rivers marked some of the boundaries.
hope this helps:-)
Answer: B
New Zealand has a mixed economy which operates on free market principles. It has sizeable manufacturing and service sectors complementing a highly efficient agricultural sector. Exports of goods and services account for around one third of real expenditure GDP
