The incorrect order of solubility in water is:

Options

A. `Ca(OH)_(2) lt Sr(OH)_(2) lt Ba(OH)_(2)`
B. `Li_(2)CO_(3) lt Na_(2)CO_(3) lt K_(2)CO_(3)`
C. `CsNO_(3) lt RbNO_(3) lt KNO_(3)`
D. `BeS_(2)O_(3) lt MgS_(2)O_(3) lt CaS_(2)O_(3)`

Answer

To determine the incorrect order of solubility in water among the given compounds, we will analyze the solubility trends of each group of compounds based on their chemical composition and the periodic table.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds given are:
- Ca(OH)₂ (Calcium hydroxide)
- Sr(OH)₂ (Strontium hydroxide)
- Ba(OH)₂ (Barium hydroxide)
- Li₂CO₃ (Lithium carbonate)
- Na₂CO₃ (Sodium carbonate)
- K₂CO₃ (Potassium carbonate)
- CsNO₃ (Cesium nitrate)
- RbNO₃ (Rubidium nitrate)
- KNO₃ (Potassium nitrate)
- BeS₂O₃ (Beryllium thiosulfate)
- MgS₂O₃ (Magnesium thiosulfate)
- CaS₂O₃ (Calcium thiosulfate)

2. **Analyze Solubility Trends**:
- For **Group 1 Hydroxides** (Ca(OH)₂, Sr(OH)₂, Ba(OH)₂): As we move down the group from calcium to barium, the solubility increases. Thus, the correct order is Ca(OH)₂ < Sr(OH)₂ < Ba(OH)₂.
- For **Group 1 Carbonates** (Li₂CO₃, Na₂CO₃, K₂CO₃): The solubility increases as we move down the group from lithium to potassium. Thus, the correct order is Li₂CO₃ < Na₂CO₃ < K₂CO₃.
- For **Group 1 Nitrates** (CsNO₃, RbNO₃, KNO₃): The solubility of nitrates generally increases down the group, but NO₃⁻ is an exception where the solubility decreases from KNO₃ to CsNO₃. Thus, the correct order is KNO₃ > RbNO₃ > CsNO₃.
- For **Thiosulfates** (BeS₂O₃, MgS₂O₃, CaS₂O₃): The anion S₂O₃²⁻ has two central atoms, and the solubility decreases as we move down the group from beryllium to calcium. Thus, the correct order is BeS₂O₃ > MgS₂O₃ > CaS₂O₃.

3. **Identify the Incorrect Order**:
- The first three groups (hydroxides, carbonates, and nitrates) have correct orders of increasing solubility.
- The last group (thiosulfates) is incorrectly stated as increasing solubility from Be to Ca, while it should actually decrease.

4. **Conclusion**: The incorrect order of solubility in water is:
- **D. BeS₂O₃ > MgS₂O₃ > CaS₂O₃** should be **CaS₂O₃ > MgS₂O₃ > BeS₂O₃**.

### Final Answer:
The incorrect order of solubility in water is **D. BeS₂O₃ > MgS₂O₃ > CaS₂O₃**.

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