The diagram below shows a box with two forces acting upon it.
20 N
20 N
Based on the diagram, which of the
following is most likely true?
A The box will move downward.
B The box will move toward the left.
C The box will move toward the
right.
D The box will not move or change
direction.

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.