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 hypothesis of continental drift came up in 1910 by German scientist Alfred Wegener. The idea is that when you look at a map south America and Africa seem to fit perfectly together. this would have made one super Continent called Pangaea. so in order for it to get to where it is today something must have happened that is where the idea of floating continents came in. this theory is no longer relevant as now scientists found they would have to adjust to fit the size if both continents. I hope this helps.
The most abundant fossil fuel is coal... Coal isn't only our most abundant fossil fuel,it's also the one with perhaps the longest history. The U.S. has more coal reserves than any other country in the world. In fact, one-fourth of the all the known coal in the world is in the U.S.
Answer:
Cadastral information system is an organized system that records land information, holdings and describe the spatial and non-spatial entities of parcels and land information.
Answer:
I think it will mean that the words of the question represent the key-words of your thesis. So you mustn't change the words of the question while writing your thesis
