It is given that a protein has a molecular weight (Mw) of 21342. It consists of 180 amino acids of which 80 are glutamine (Mw of anhydro residue = 128.1), 60 are histidine (Mw of anhydro residue 137.2) and 40 alanine (Mw of anhydro residue 71.1). At both the C-terminal and the N-terminal position an alanine residue is present.

4al + 3o2 → 2al2o3 what does the "3" in front of o2 stand for? a) it indicates that there are 5 oxygen atoms after you add the coefficient and the subscript. b) it indicates that that there are are total of 6 oxygen atoms all bonded together as a single molecule. c) it indicates that there are 3 oxygen molecules chemically bonded to each other in the reaction. d) it indicates that there are 3 separate oxygen molecules in the reaction.