Atypical adult human lung contains about 330 million tiny cavities called alveoli. estimate the average diameter of a single alveolus. assume the alveoli are spherical and a typical human lung is about 1.9 liters.

Regarding the history of the universe, which of the following is true? all the chemical elements were created during the big bang, but some have been modified since that time as a result of radioactive decay. the earth formed quickly after the big bang. all the current stars in our galaxy formed about the same time billions of years ago. key elements of which earth and life are made, including carbon, oxygen, and iron, did not exist when the universe was born and were created later in stars.