What is true of all atoms? A They are electrically charged. incorrect answer
B They contain more than one electron shell. incorrect answer
C They have full outer electron shells. incorrect answer
D They contain at least one proton.

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.

gasoline is a mixture. it contains several different kinds of compounds that can be present in a variety of ratios.