Which of the following are arranged in correct increasing order of solubilities ?

Options

A. `CaCO_(3) lt KHCO_(3) lt NaHCO_(3)`
B. `NaHCO_(3) ltKHCO_(3) lt CaCO_(3)`
C. `KHCO_(3) lt NaHCO_(3) lt CaCO_(3)`
D. `CaCO_(3) lt NaHCO_(3) lt KHCO_(3)`

Answer

To solve the question regarding the increasing order of solubilities of the given compounds, we can follow these steps:

### Step 1: Identify the Compounds and Their Groups
We are given bicarbonates of sodium (NaHCO3) and potassium (KHCO3), and the carbonate of calcium (CaCO3).
- Sodium (Na) and potassium (K) are alkali metals (Group 1).
- Calcium (Ca) is an alkaline earth metal (Group 2).

### Step 2: Understand Solubility Trends in Group 1 and Group 2
- **Group 1 (Alkali Metals)**: The solubility of their compounds generally increases as we move down the group. Hence, KHCO3 (potassium bicarbonate) is more soluble than NaHCO3 (sodium bicarbonate).
- **Group 2 (Alkaline Earth Metals)**: The solubility of their carbonates generally decreases as we move down the group. Therefore, CaCO3 has lower solubility compared to the alkali metal bicarbonates.

### Step 3: Compare Solubilities
From the above trends:
- CaCO3 will have the least solubility among the three compounds.
- Between NaHCO3 and KHCO3, KHCO3 will have higher solubility than NaHCO3.

### Step 4: Arrange in Increasing Order of Solubility
Based on the analysis:
1. CaCO3 (least soluble)
2. NaHCO3
3. KHCO3 (most soluble)

Thus, the correct increasing order of solubilities is:
**CaCO3 < NaHCO3 < KHCO3**

### Final Answer
The correct answer is that the increasing order of solubilities is:
**CaCO3 < NaHCO3 < KHCO3**

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