Oxygen by volume has a presence in atmosphere of about: Admin January 16, 2019 Biology MCQs, General Science MCQs Comments A. 10%B. 21%C. 32%D. 44% Related Posts:During the day time, plants:Cork cells are impervious to water because of the…Plants receive nutrients mainly from:The lowest zone of atmosphere containing about 75%…Water helps in the metabolism process in the presence of:Lightest Gas in world is: