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 average atomic mass of hydrogen is 1.00794. amu. This shows that the most common isotope has a mass of. (1) 1 amu, (2) 2 amu, (3) 3 amu, (4) 4 amu. 2. Chlorine occurs naturally as two common isotopes, 35Cl and 37Cl. Which of the following percentages results in the average mass of.