Question

The correct statement about iron includes
$\left(I\right)$ the highest oxidation state of iron is $+6$ in $K_{2}Fe{O}_4$
$\left(II\right)$ that the iron shows $+2$ oxidation state with six electrons in the unfilled $3d$ orbitals
$\left(III\right)$ the common oxidation state of iron is $+3$ with five unpaired electrons in the $3d$ orbital.

• A. $I$ only
• B. $I,II$
• C. $II,III$
• D. $I,II,III$

Answer 1

The correct option is A $I$ only

(i) The highest oxidation state of iron is +6 in $K_{2}Fe{O}_4$ as 3d subshell contains 2 paired and 4 unpaired electrons.
These four unpaired electrons in 3d and 2 electrons in 4s give rise to +6 oxidation state.
Hence, statement (i) is true.

(ii) The electronic configuration of Fe and $F{e}^{2+}$ are $3d^{6}4s^2$ and $3d^4{s}^0$ respectively.
Thus two 4s electrons are lost to form +2 oxidation state. Six electrons remain in unfilled 3d orbitals.
hence, the statement (ii) is true.

(iii) +2 and +3 are the common oxidation states of iron with 4 and 5 unpaired electrons respectively in the 3d orbital.
Hence, statement (iii) is true.

Hence, the correct option is $\text{D}$