CaO forms a solid solution with Bi2O3 to give a material with a high anionic conductivity. If 10 mol% CaO is reacted with 90 mol% Bi2O3, what is the formula of the final solid and what are the numbers and types of vacancies created

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.