The science department has gotten together to make neon signs for their classrooms. Given we are under STP conditions, and our neon tubes each hold a volume of 0.55 L, what is the mass of neon in each tube? 'hint: you need moles in order to get to mass

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.