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 molar mass of an element is it's atomic mass in g â¦ rams. The atomic mass of oxygen is 15.999. Since there are two atoms of oxygen in a molecule of oxygen, the molar mass of oxgen (O2) is 15.999 x 2. That comes out to 31.998g/mol, or you can round to 32 if significant figures arn't important to you.