Answer:
20.9 percent
Around 78% of the air is nitrogen gas, and only 20.9% is oxygen.
Explanation:
20.9 percent
Around 78% of the air is nitrogen gas, and only 20.9% is oxygen.
Hope this helps.
Your muscles. Some muscles are “voluntary.” They
are the ones you control, the ones that let you exercise—or
relax. Some muscles are “involuntary.” They just do their
job with no effort on your part—like your heart muscles.
