Watch all the terms that apply to each element. Some terms may apply to more than one element. noble gas
alkaline earth
element
inner transition
metal element
main group
element
metalloid
transition metal
element
alkali metal
metal
nonmetal
halogen
a. Phosphorus
b. Fluorine
c. Potassium
d. Iron

it's c (engineer's do their work with mechanical stuff not on any living being)

i belive it is water

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.