Question

Match the column I with column II and mark the appropriate choice.

Column $I$ (Compound)		Column $II$ (Oxidation state of Fe)
(A)	$K_3[Fe(OH)_6$	(i)	$+8/3$
(B)	$K_2[FeO_4]$	(ii)	$+2$
(C)	$FeSO_4\cdot(NH_4)_2SO_4\cdot6H_2O$	(iii)	$+3$
(D)	$Fe_3O_4$	(iv)	$+6$

• A. (A) $\to$ (iii), (B) $\to$ (i), (C) $\to$ (ii), (D) $\to$ (iv)
• B. (A) $\to$ (iii), (B) $\to$ (iv), (C) $\to$ (ii), (D) $\to$ (i)
• C. (A) $\to$ (i), (B) $\to$ (iii), (C) $\to$ (ii), (D) $\to$ (hr)
• D. (A) $\to$ (iv), (B) $\to$ (ii), (C) $\to$ (i), (D) $\to$ (iii)

Answer 1

Answer: (B)

$K_{3}\left[Fe\left(OH\right)_{6}\right] \to+3 + x - 6 = 0 \Rightarrow x = +3$
$K_{2}\left[FeO_{4}\right] \to+2 + x - 8 = 0 \Rightarrow x = +6$
$FeSO_{4}\cdot\left(NH_{4}\right)_{2}SO_{4}\cdot6H_{2}O, in FeSO_{4} \to x-2 = 0 \Rightarrow x=+2$
$Fe_{3}O_{4 }= FeO + Fe_{2}O_{3} \to x - 2 + 2x - 6 = 0$
$\Rightarrow 3x = +8 \Rightarrow x = +8/3$