Vitamin K antagonists (VKA) are a group of substances that reduce blood clotting by reducing the action of vitamin K. They are used as anticoagulant medications in the prevention of thrombosis, and in pest control, as rodenticides. 1  1 Mechanism of action.  2 Coumarins (4-hydroxycoumarins)
Calculate the average atomic mass of oxygen. Solution: ((15.994915*99.757) + (16.999132*0.038) + (17.999160*0.205))/100 = 15.999405 . Using our equation for determining average atomic mass, we see that the average atomic mass for oxygen is 15.999405 amu. If we check the periodic table, we will see that our average atomic mass is the same as the atomic mass indicated on the element oxygen. Ã
The mass of oxygen in this amount of water therefore is 0.888 X 52.8 = 46.9 grams. The molecular mass of oxygen atoms is 2 X 15.999 = 32.0, so that 46.9 grams corresponds to 46.9/32.0 = 1.466 moles of oxygen molecules.onfidence votes 68. Oxygen is a diatomic gas, so a molecule of oxygen contains two oxygen atoms. One oxygen atom has an atomic weight of 16.00 amu (atomic mass units), so diatomic oxygen has a molecular weight of 16.00 Ã 2 or 32.00 amu.