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 apply the solubility rules outlined in the video transcript. Let's analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the Compounds**:
We have the following compounds to analyze:
- A) Na2CO3 (Sodium Carbonate)
- B) BaC2O4 (Barium Oxalate)
- C) MgCO3 (Magnesium Carbonate)
- D) Ca(NO3)2 (Calcium Nitrate)

2. **Apply Solubility Rules**:
- **Rule 1**: All nitrates (NO3-) are soluble in water.
- **Rule 2**: All alkali metal salts (including carbonates of alkali metals) are soluble in water.
- **Rule 3**: Oxalates (C2O4^2-) are generally insoluble, with some exceptions.
- **Rule 4**: Carbonates (CO3^2-) are generally insoluble, except for those of alkali metals and ammonium.

3. **Analyze Each Compound**:
- **A) Na2CO3**:
- Sodium (Na) is an alkali metal. According to Rule 2, all alkali metal carbonates are soluble in water.
- **Conclusion**: Na2CO3 is soluble in water.

- **B) BaC2O4**:
- Barium oxalate is an oxalate. According to Rule 3, oxalates are generally insoluble.
- **Conclusion**: BaC2O4 is insoluble in water.

- **C) MgCO3**:
- Magnesium carbonate is a carbonate. According to Rule 4, carbonates are generally insoluble, except for alkali metals and ammonium.
- **Conclusion**: MgCO3 is insoluble in water.

- **D) Ca(NO3)2**:
- Calcium nitrate contains nitrate ions. According to Rule 1, all nitrates are soluble in water.
- **Conclusion**: Ca(NO3)2 is soluble in water.

4. **Final Summary**:
- The soluble compounds are:
- A) Na2CO3 (soluble)
- D) Ca(NO3)2 (soluble)
- The insoluble compounds are:
- B) BaC2O4 (insoluble)
- C) MgCO3 (insoluble)

### Final Answer:
The compounds that are soluble in water are:
- A) Na2CO3
- D) Ca(NO3)2