1 part per billion by weight, 0.2 parts per billion by moles.
supernovae
A lot
4
The distance from Earth to the sun is much greater than from Earth to the moon. It is not possible that the sun would be between Earth and the moon.
Fresh water covers approximately 0.7% of the Earth's surface, found in locations such as rivers, lakes, and groundwater. Most of Earth's water is found in oceans and seas, which are composed of saltwater.
Africa, but that doesn't help much probably. Keep searching!!
there are birds,insects,mammals,amphibians and much more
The moon is made of rock much like that found on Earth.
99%
the answer is about 65%
Neptunium is an artificial element.Amounts of natural neptunium are absolutely nonsignificant.
BBC Earth gives many updates about the Earth's natural phenomenons. One can find more information about Earth's landmarks, recent earthquakes, and much more on BBC Earth.