Amixture of ar, he, and o2 has a total pressure of 1,015 kpa. argon exerts a partial pressure of 152 kpa and helium exerts a partial pressure of 305 kpa. what is the partial pressure of oxygen in this mixture?
a.1,472 kpa
b.558 kpa
c.863 kpa
d.710 kpa

This one is easy. It's just addition and subtraction. Add the partial pressure of Argon and the partial pressure of Helium:
   152 kPa
+305 kPa
  457 kPa

Next, subtract the result from the total pressure:

  1015 kPa
-  457 kPa
   558 kPa

Answer : option a) 84explanation :

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.

H tricky one let me think and get back to u