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
Normal oxygen has atomic mass 16, hydrogen 1, water has 1 oxygen and 2 hydrogen, so the total molecular mass of water is 18. Therefore, we are talking about one mole of water.This mole of water has 6 x 10 23 atoms of oxygen, twice as many atoms of hydrogen.his mole of water has 6 x 10 23 atoms of oxygen, twice as many atoms of hydrogen.