Both cation and impurities can be removed from hard water by using

Options

A. Zeolites
B. Organic ion exchanges
C. Calgon
D. All of these

Answer

To solve the question "Both cation and impurities can be removed from hard water by using," we need to evaluate the given options and determine which method effectively removes both cations and impurities from hard water.

### Step-by-Step Solution:

1. **Understand Hard Water**:
- Hard water contains dissolved minerals, primarily calcium (Ca²⁺) and magnesium (Mg²⁺) ions, along with other impurities like sulfate (SO₄²⁻) and chloride (Cl⁻) ions.

2. **Evaluate the Options**:
- **Option 1: Zeolites**:
- Zeolites are sodium aluminum silicates that can exchange sodium ions (Na⁺) for calcium (Ca²⁺) and magnesium (Mg²⁺) ions in hard water.
- While zeolites can reduce hardness, they do not completely remove all impurities. The exchanged ions can still form complexes that remain in solution.

- **Option 2: Organic Ion Exchange**:
- This method involves passing hard water through two chambers: a cation exchange chamber and an anion exchange chamber.
- In the cation exchange chamber, calcium and magnesium ions are exchanged for hydrogen ions (H⁺).
- In the anion exchange chamber, sulfate and chloride ions are exchanged for hydroxide ions (OH⁻).
- This process effectively removes both cations and impurities, resulting in soft water.

- **Option 3: Calgan Method**:
- Calgan is a complexing agent that can bind to calcium ions. However, it does not completely remove these ions from the water; instead, it forms complexes that remain in solution.
- Therefore, it is not effective for complete removal of cations and impurities.

- **Option 4: All of These**:
- Since not all methods listed are effective in completely removing cations and impurities, this option is incorrect.

3. **Conclusion**:
- The most effective method for removing both cations and impurities from hard water is the **Organic Ion Exchange** method.

### Final Answer:
The correct option is **Organic Ion Exchange**.

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