Some chemicals, most often inorganic salts, in the laboratory have the nasty tendency to absorb water from the atmosphere. This property is called

hygroscopicity. Anhydrous (water-free) Cupric Perchlorate [Cu(ClO4)2]

weighs 262.447g/mol, but after sitting on out on the benchtop absorbs water from the air and now weighs 370.540g/mol. How many water

molecules did our Cupric Perchlorate absorb?

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.