Which of the following ores is a double salt composition

Options

A. Carnallite
B. Alum
C. Dolomite
D. Cerrusite

Explanation

To determine which of the following ores is a double salt composition, we need to understand what a double salt is. A double salt is a compound that contains more than one cation or anion, and when dissolved in water, it dissociates into its constituent salts.

### Step-by-Step Solution:

1. **Understanding Double Salts**:
- A double salt consists of two different salts that combine to form a single crystalline structure. When dissolved in water, it separates into its individual ions.

2. **Analyzing the Given Ores**:
- We have four ores to analyze: Carnalite, LM, Dolomite, and Keroside.

3. **Carnalite**:
- Formula: KCl·MgCl2·6H2O
- Contains: K⁺ (potassium ion) and Mg²⁺ (magnesium ion).
- Since it contains two different cations (K⁺ and Mg²⁺), it qualifies as a double salt.

4. **LM**:
- Formula: K2SO4·Al2(SO4)3·24H2O
- Contains: K⁺ (potassium ion) and Al³⁺ (aluminum ion).
- This also contains two different cations (K⁺ and Al³⁺), making it a double salt.

5. **Dolomite**:
- Formula: CaCO3·MgCO3
- Contains: Ca²⁺ (calcium ion) and Mg²⁺ (magnesium ion).
- It has two different cations (Ca²⁺ and Mg²⁺), so it is also a double salt.

6. **Keroside**:
- Formula: PbCO3
- Contains: Pb²⁺ (lead ion) and CO3²⁻ (carbonate ion).
- This does not qualify as a double salt because it contains only one cation (Pb²⁺) and one anion (CO3²⁻).

7. **Conclusion**:
- The ores that qualify as double salt compositions are Carnalite, LM, and Dolomite. Keroside does not qualify.

### Final Answer:
The ores that are double salt compositions are **Carnalite, LM, and Dolomite**.