Titanium (IV) oxide, TiO2, is a white substance produced by the action of sulfuric acid on the mineral ilmenite, FeTiO3: H2SO4 + FeTiO3 TiO2 + FeSO4 + H2O
Its opaque and nontoxic properties make it suitable as a pigment in plastics and paints. In one process, 817 g of ilmenite reacts to produce how many grams of TiO2?

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.