Answer:
4s^2
Explanation:
Scandium is the first member of the first transition series having an atomic number of 21.
The ground state electron configuration of scandium is:;
1s2 2s2 2p6 3s2 3p6 3d1 4s2.
We can see from the electron configuration written above that the highest occupied energy sublevel for scandium is the 4s level having two electrons.