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

Options

A. II,III in haematite and III in magnetite
B. II,III in haematite and II in magnetite
C. II in haematite and II, III in magnetite
D. III in haematite and II, III in magnetite

Answer

To determine the oxidation states of the metal in the minerals haematite and magnetite, we will analyze their chemical formulas and apply the rules for oxidation states.

### Step-by-Step Solution:

1. **Identify the formulas of the minerals:**
- Haematite has the formula **Fe₂O₃**.
- Magnetite has the formula **Fe₃O₄**.

2. **Calculate the oxidation state of iron (Fe) in haematite (Fe₂O₃):**
- In Fe₂O₃, oxygen (O) has an oxidation state of -2.
- The total contribution from oxygen in the formula is:
\[ 3 \times (-2) = -6 \]
- Let the oxidation state of iron be \( x \). Since there are 2 iron atoms, the equation becomes:
\[ 2x + (-6) = 0 \]
- Solving for \( x \):
\[ 2x - 6 = 0 \implies 2x = 6 \implies x = 3 \]
- Therefore, the oxidation state of iron in haematite is **+3**.

3. **Calculate the oxidation state of iron (Fe) in magnetite (Fe₃O₄):**
- Magnetite can be considered as a mixed oxide, represented as FeO·Fe₂O₃.
- For FeO:
- The oxidation state of O is -2, so for Fe:
\[ x + (-2) = 0 \implies x = +2 \]
- For Fe₂O₃ (already calculated):
- The oxidation state of Fe is +3.
- Therefore, in magnetite, iron has two different oxidation states: **+2** and **+3**.

4. **Summarize the results:**
- The oxidation state of iron in haematite (Fe₂O₃) is **+3**.
- The oxidation states of iron in magnetite (Fe₃O₄) are **+2** and **+3**.

### Final Answer:
- The oxidation states of the metal in haematite and magnetite, respectively, are **+3** and **+2, +3**.