Which of the following compounds is alkaline in aqueous medium ?

Options

A. `Na_(2)CO_(3)`
B. `NaCl`
C. `NaCO_(3)`
D. `CuSO_(4)`

Explanation

To determine which of the following compounds is alkaline in aqueous medium, we will analyze each compound provided: Na2CO3, NaCO3, NaCl, and CuSO4.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- The compounds given are Na2CO3 (sodium carbonate), NaCO3 (which is not a valid compound), NaCl (sodium chloride), and CuSO4 (copper(II) sulfate).

2. **Analyze Na2CO3**:
- When Na2CO3 is dissolved in water, it dissociates into sodium ions (Na⁺) and carbonate ions (CO3²⁻).
- The carbonate ions can react with water to form bicarbonate (HCO3⁻) and hydroxide ions (OH⁻), which increases the pH of the solution, making it alkaline.
- Therefore, Na2CO3 produces NaOH (sodium hydroxide), a strong base, in solution.

3. **Analyze NaCO3**:
- NaCO3 is not a recognized compound; it is likely a typographical error or misrepresentation of sodium carbonate (Na2CO3). Thus, we will not consider it further.

4. **Analyze NaCl**:
- When NaCl is dissolved in water, it dissociates into sodium ions (Na⁺) and chloride ions (Cl⁻).
- This solution remains neutral because neither ion affects the pH significantly. Therefore, NaCl does not produce an alkaline solution.

5. **Analyze CuSO4**:
- When CuSO4 is dissolved in water, it dissociates into copper ions (Cu²⁺) and sulfate ions (SO4²⁻).
- This solution is also neutral and does not exhibit alkaline properties.

6. **Conclusion**:
- Among the compounds analyzed, only Na2CO3 produces an alkaline solution in aqueous medium due to the formation of NaOH.

### Final Answer:
The compound that is alkaline in aqueous medium is **Na2CO3** (sodium carbonate).

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