2. How has scientific understanding about the composition of the universe changed over time? Select the two correct answers. The percentage of dark matter has shrunk in scientists' estimates since the 1980s
The percentage of unknown material has grown in scientists' estimates since the 1970%
The percentage of ordinary matter has grown in scientists' estimates.
The percentage of dark energy has shrunk in scientists estimates

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex

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what do the different brain waves do?

explanation:

brainwaves are produced by synchronised electrical pulses from masses of neurons communicating with each other. brainwaves are detected using sensors placed on the scalp. brainwave speed is measured in hertz (cycles per second) and they are divided into bands delineating slow, moderate, and fast waves.

the correct answer is - d. china has a large and growing population.

the fact that china has a large (the biggest) population, and it is still growing, doesn't hinder the agriculture production in the country. in fact, it can for increased production in the agriculture, since there's more labor force, as well the sheer mass of people produces lots of scientists that come up with new inventions as to how to improve this sector. nice example is the inner mongolia region in china, in general dominated by the gobi desert, but few scientist came up with a nice idea as to how to make the region productive by using plants that are very resistant to droughts, so lots of people have been employed, and the region is becoming greener and greener each year, and the production of food in this region is also increasing.

"it built up in the atmosphere"

i think thats it, idk, i tried looking for this exact q& a for grad. and idk if i got this question right or sorry if im wrong