Answer
See the answer below.
Work Step by Step
a) 113: $[Rn]\ 5f^{14}\ 6d^{10}\ 7s^2\ 7p^1$
115: $[Rn]\ 5f^{14}\ 6d^{10}\ 7s^2\ 7p^3$
b) 113: Group 13, Boron
115: Group 15, Nitrogen
c) Americium's atomic number: 95
Atomic number of the lighter atom: 113-95=18
That's argon.
