State the electron configurations of the following metal ions by filling in the boxes below. Use arrows to represent the electron spin.
| Ion | 3d | | | | | 4s |
|---|----|--|--|--|--|----|
| Sc 3+ | | | | | | |
| Ti 3+ | | | | | | |
| Ni 2+ | | | | | | |
| Zn 2+ | | | | | | |