Question

Select the set having incorrect statements given here.
(i) Manganese exhibits +7 oxidation state
(ii) Zinc forms coloured ions
(iii) $[\text{Co}{\text{F}}_6{]}^{3-}$ is diamagnetic
(iv) Sc forms +4 oxidation state
(v) Zn exhibits only +2 oxidation state

• A. (i), (ii) and (iii)
• B. (ii), (iii) and (iv)
• C. (i), (iii) and (iv)
• D. (i), (iii) and (v)

Answer 1

Answer: (B)

Outer electronic configuration of Mn is $\text{3}{\text{d}}^5\text{4}{\text{s}}^2$ which means it can show +7 oxidation state also (correct)
Zinc does not form coloured ions as it has completely filled $\text{3}{\text{d}}^{10}\text{4}{\text{s}}^2$ configuration.
In $[\text{Co}{\text{F}}_6{]}^{3-},\text{C}{\text{o}}^{3+}$ is a $d^6$ system. Fluoride is a weak field ligand and hence it can not cause pairing of electrons.

Sc can show a maximum of +3 oxidation state as it has an outer electronic configuration of $\text{3}{\text{d}}^1\text{4}{\text{s}}^2$ .
Zn exhibits only +2 oxidation state as this oxidation state is the most stable one for it.
Hence (ii), (iii), (iv) are incorrect while (i), (v) are correct.