What is the maximum number of electrons that can occupy a box in an orbital filling diagram at any energy level?

it should have an internal chamber and two thermometers sticking out of the top. the internal chamber will also be closed off from the outside.

i believe the answer is three water molecules

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.