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
How many protons neutrons and electrons are in oxygen? Oxygen has a mass number of 16.00 with atomic number 8 which means there are 8 electrons and 8 protons. The number of neutrons is always equal to the mass number- the atomic nâ¦umber. In this case it is 16 - 8= 8. Protons: 8 Neutrons: 8 (for isotope O16 the most common) Electrons: 8.