14.(a)Explain the change in mass expected when each of the following substances is heated in an open crucible.
( i)Copper metal.
(ii)Copper (II) nitrate
(b)A certain mixture consists of zinc oxide, iron (III) chloride and potassium chloride sohids.
Describe how you can obtain a solid sample of each of the components of the mixture.​

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.