Which of the following statements about the composition of earths atmosphere is true?
a)earths atmosphere contains 78% water vapor which is essential to life.
b)earths atmosphere contains 21% oxygen.
c)earths atmosphere contains carbon dioxide which all life forms require.
d)earths atmosphere allows radiation from the sun to pass through it and warm earths surface.
a)earths atmosphere contains 78% water vapor which is essential to life.
b)earths atmosphere contains 21% oxygen.
c)earths atmosphere contains carbon dioxide which all life forms require.
d)earths atmosphere allows radiation from the sun to pass through it and warm earths surface.