Analysis of air bubbles trapped in fossils, such as in fossil amber, show that our air in earliest times contained about 35% oxygen. Today, the average oxygen content of our air is approximately 20%. In some larger, more polluted cities, oxygen content in the air has been measured at 12 - 15%.
There are 297 words which start with 'pen'. 3 letter words starting with 'pen': pen. 4 letter words starting with 'pen': pend. pens.
A list of words that start with Iso (words with the prefix Iso). We search a large scrabble dictionary for scrabble words starting with iso-we take the letter or word you enter, and generate all words starting with Iso. In addition there is a list of Words that end with iso, words that contain iso. Search for words that start with a letter or word: 11 Letter words that start with iso. 1  Isoantibody.