What is strong acid?​

Acid strength is the tendency of acid, symbolized by the chemical formula, to dissociate into a proton, and an anion. The dissociation of a strong acid in solution is effectively complete, except in its most concentrated solution.

Explanation:

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.