JEE Advanced · 2011 · 10 Apr 2011 · Paper 2 · General Principles and Processes of Isolation of Metals

Oxidation states of the metal in the minerals haematite and magnetite, respectively, are

Answer: (D)

Solution

Haematite is

Fe_{2} O_{3}

. Setting up the oxidation state equation:

2 x + 3 (- 2) = 0

, so

x = + 3

.

Magnetite is

Fe_{3} O_{4}

, which is an equimolar mixture of

FeO

and

Fe_{2} O_{3}

. In

FeO

x - 2 = 0

, so

x = + 2

. In

Fe_{2} O_{3}

x = + 3

.

Therefore, haematite has Fe in +III state, and magnetite has Fe in both +II and +III states.

JEE Advanced · 2011 · 10 Apr 2011 · Paper 2 · Single correct option