Answer:
The average atomic mass of X is 206.0346
Explanation:
Atomic mass of 200X = 200.028
% abundance of 200X = 40% = 40/100 = 0.4
Atomic mass of 210X = 210.039
% abundance of 210X = 100% - 40% = 60% = 60/100 = 0.6
Average atomic mass of X = (0.4×200.028) + (0.6×210.039) = 80.0112 + 126.0234 = 206.0346
Answer: D. There is a lot of light pollution on earth
Explanation: The light pollution on Earth has nothing to do with the stars in the sky
<span>The value of the constant needed to complete in joules to three significant figures is 2.18 x 10^-18 J.</span>
Land: Tectonic plate movement under the Earth can create landforms by pushing up mountains and hills. Erosion by water and wind can wear down land and create landforms like valleys and canyons. ... Landforms can exist under water in the form of mountain ranges and basins under the sea.
Atmosphere: (4.6 billion years ago)
As Earth cooled, an atmosphere formed mainly from gases spewed from volcanoes. It included hydrogen sulfide, methane, and ten to 200 times as much carbon dioxide as today's atmosphere. After about half a billion years, Earth's surface cooled and solidified enough for water to collect on it.
Ocean: After the Earth's surface had cooled to a temperature below the boiling point of water, rain began to fall—and continued to fall for centuries. As the water drained into the great hollows in the Earth's surface, the primeval ocean came into existence. The forces of gravity prevented the water from leaving the planet.
Lose electrons because they have a negative charge.
