Which of these phrases best explains how geographers use the word place? A.
to show how natural processes are changing the Earth
B.
to describe the characteristics of a location
C.
to explain how areas are grouped together into regions
D.
to discuss the location of a certain area

gas

explanation:

smoke is the matter of a gas

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.