Oxygen group? (4E - Chemical and Physical Foundations)

Hi, I was studying for category 4E. This was listed on the AAMC MCAT website. I could not find much for it on Khan Academy or my previous notes and textbooks. Can someone help me out, please and thank you!
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: MCAT: Medical College Admissions Test Source Type: forums