Answer
See the answer below.
Work Step by Step
In order to create the noble gas configuration, look for the noble gas that comes before the given element. Then, starting at that element, write the correct electron configuration.
a) As, group 15, period 4: $[Ar]\ 3d^{10}\ 4s^2\ 4p^3$.
b) Kr, group 18, period 4: $[Ar]\ 3d^{10}\ 4s^2\ 4p^6$
