Answer to Question 1
Hydrogen.
Answer to Question 2
Once the usable hydrogen fuel is all burned up, there remains a helium-rich core. Once fusion is finished in the star's core, there is insufficient pressure to prevent collapse due to gravity, and the contraction generates a huge increase in internal temperature, triggering a higher level of hydrogen fusion in the star's shell. The outer shell expands from the heat of accelerated fusion, but this expansion simultaneously cools the star's surface, yielding a large, cool star.
Much of the dark space between stars, as seen in the sky of the image above, is due to the human eye
The more air and fuel that can be packed in a cylinder, the greater the density of the air–fuel ...
Metabolic adaptations promote alternative fuel use during starvation
Sequence of nucleotides in a DNA molecule
A fictional element named Nivadium is found to have three naturally occurring is
Cladogram Based On DNA Sequence