Which of the following anions are easily removed from aqueous solution by precipitation ?

Options

A. `Cl^(Θ)`
B. `SO_(4)^(2-)`
C. `NO_(3)^(Θ)`
D. `CO_(3)^(2-)`

Explanation

To determine which anions can be easily removed from aqueous solution by precipitation, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Anions**: The options given are chloride ions (Cl⁻), sulfate ions (SO₄²⁻), nitrate ions (NO₃⁻), and carbonate ions (CO₃²⁻).

2. **Analyze Chloride Ion (Cl⁻)**:
- When chloride ions are treated with silver nitrate (AgNO₃), they form silver chloride (AgCl), which is a white precipitate.
- **Conclusion**: Chloride ions can be easily removed by precipitation.

3. **Analyze Sulfate Ion (SO₄²⁻)**:
- Sulfate ions can react with barium ions (Ba²⁺) to form barium sulfate (BaSO₄), which is also a white precipitate.
- **Conclusion**: Sulfate ions can be easily removed by precipitation.

4. **Analyze Nitrate Ion (NO₃⁻)**:
- Nitrate ions are generally soluble in water and do not form precipitates with common cations.
- **Conclusion**: Nitrate ions cannot be easily removed by precipitation.

5. **Analyze Carbonate Ion (CO₃²⁻)**:
- Carbonate ions can react with calcium ions (Ca²⁺) or magnesium ions (Mg²⁺) to form calcium carbonate (CaCO₃) or magnesium carbonate (MgCO₃), both of which are precipitates.
- **Conclusion**: Carbonate ions can be easily removed by precipitation.

### Final Answer:
The anions that can be easily removed from aqueous solution by precipitation are:
- Chloride ions (Cl⁻)
- Sulfate ions (SO₄²⁻)
- Carbonate ions (CO₃²⁻)

Thus, the correct options are 1 (Cl⁻), 2 (SO₄²⁻), and 4 (CO₃²⁻).

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