Explanation:
It is given that r = 0.283 nm. As 1 nm = .
Hence, 0.283 nm =
where, e = C
=
So, 1 J =
Hence, U =
= 8.9 eV
= kJ/mol
Therefore, U = kJ/mol
The element with 8 electrons in its 3d sublevel is Ni, Nickel. The answer is letter D. The rest of the choices do not answer the question above.