How often does oxygen cycle through the atmosphere?
a. about every 1000 years
b. about every 1500 years
c. about every 2000 years
d. about every 2500 years

a) carbon, hydrogen

b) carbon, hydrogen, oxygen, nitrogen

c) carbon, hydrogen, oxygen, nitrogen, phosphorus

d) sugar

e) amino acid

f) nucleotide

explanation:

the sun shines white and black light to our planet. the white light has all the colors in it. in our upper atmosphere, we have dust particles and oxygen molecules. the white light meaning all of the colors in a rainbow shines through the upper levels of the atmopshere and the blue light scatters across the entire planet. that is why our sky is blue.