Which of the following are soluble in water?

Options

A. `Na_(2)CO_(3)`
B. `BaC_(2)O_(4)`
C. `MgCO_(3)`
D. `Ca(NO_(3))_(2)`

Answer

To determine which of the given compounds are soluble in water, we will analyze each option based on solubility rules.

### Step-by-Step Solution:

1. **Identify the Compounds:**
- Option 1: Na2CO3 (Sodium Carbonate)
- Option 2: BaC2O4 (Barium Oxalate)
- Option 3: MgCO3 (Magnesium Carbonate)
- Option 4: Ca(NO3)2 (Calcium Nitrate)

2. **Analyze Option 1: Na2CO3**
- Sodium carbonate (Na2CO3) is a salt of an alkali metal (sodium). According to solubility rules, all alkali metal carbonates are soluble in water.
- **Conclusion:** Na2CO3 is soluble in water.

3. **Analyze Option 2: BaC2O4**
- Barium oxalate (BaC2O4) is an oxalate. According to solubility rules, most oxalates are insoluble in water, with the exception of those of alkali metals and ammonium.
- **Conclusion:** BaC2O4 is insoluble in water.

4. **Analyze Option 3: MgCO3**
- Magnesium carbonate (MgCO3) is a carbonate. According to solubility rules, most carbonates are insoluble in water, except for those of alkali metals and ammonium.
- **Conclusion:** MgCO3 is insoluble in water.

5. **Analyze Option 4: Ca(NO3)2**
- Calcium nitrate (Ca(NO3)2) is a nitrate. According to solubility rules, all nitrates are soluble in water.
- **Conclusion:** Ca(NO3)2 is soluble in water.

### Final Summary:
- **Soluble Compounds:**
- Na2CO3 (Option 1)
- Ca(NO3)2 (Option 4)

- **Insoluble Compounds:**
- BaC2O4 (Option 2)
- MgCO3 (Option 3)

### Answer:
The compounds that are soluble in water are **Na2CO3 and Ca(NO3)2**.

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