Complete each statement without looking at your notes:

1. The electronic configuration of Cr is [Ar] ________ because the ________ d-subshell has extra stability.

2. $KMnO_{4}$ in acidic medium gives ________ (colour: ________), gaining ________ electrons per Mn.

3. $KMnO_{4}$ in neutral medium gives ________ (colour: ________), gaining ________ electrons per Mn.

4. $KMnO_{4}$ in basic medium gives ________ (colour: ________), gaining ________ electron per Mn.

5. The chromate ion $CrO_{4}^{2-}$ is ________ (colour) and is found in ________ (acidic/basic) solution.

6. The lanthanoid contraction makes ________ and ________ (Group 4 elements) nearly identical in size.

7. In CFT, octahedral splitting gives ________ as the lower set and ________ as the higher set.

8. Tetrahedral crystal field splitting: $\Delta t$ = ______ × $\Delta o$.

9. The magnetic moment formula is μ = ________ BM, where n is ________.

10. EDTA is a ________ dentate ligand with charge ________.

11. Vitamin $B_{12}$ contains ________ as the central metal ion with oxidation state ________.

12. An ambidentate ligand can bind through ________ different donor atoms. Example: $NO_{2}^{-}$ binds via ________ (nitro) or via ________ (nitrito).

13. In inner orbital complexes (VBT), the metal uses ________ orbitals; in outer orbital, it uses ________ orbitals.

14. The spectrochemical series from weakest to strongest: ________ < ________ < ________ < ________ < ________ < $H_{2}O$ < $NH_{3}$ < en < $NO_{2}^{-}$ < $CN^{-}$ < CO.

Answers: 1. 3$d^{5}$ 4$s^{1}$, half-filled. 2. $Mn^{2+}$, colourless, 5. 3. $MnO_{2}$, brown, 3. 4. $MnO_{4}^{2-}$, green, 1. 5. Yellow, basic. 6. Zr, Hf. 7. t_{2}g, eg. 8. 4/9. 9. √(n(n+2)), number of unpaired electrons. 10. Hexadentate, −4. 11. $Co^{3+}$. 12. Two; N; O. 13. (n−1)d, nd. 14. $I^{-}$ < $Br^{-}$ < $Cl^{-}$ < $F^{-}$ < $OH^{-}$.