What is a mass defect? O A. The error in atomic mass measurement due to electron
contributions
O B. The amount of mass lost as subatomic particles in a nuclear
reaction
O C. Too much mass gained in a nucleds as a result of nuclear fusion
O D. The amount of mass missing from a nucleus when compared with
the sum of its parts
SUBMIT

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.

4d^55s^1 ( third choice)