C) a voltaic cell consists of zn/zn2+ half-cell and a ni2+/ni half-cell at 25°c.
i. what is the initial concentration if the initial concentration of ni2+ and zn2+ are
1.75 m and 0.15 m, respectively?
ii. what is the cell potential when the concentration of ni2+ has fallen to 0.45 m?
ii.
what is the number mole of zn2+ in 500 ml solution if ecell is 0.6 v and [ni2+]
is 2.8 m

what does the table look like

a is the correct answer

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.