Among the following group-I carbonate having highest solubility ?

Options

A. `LiCO_(3)`
B. `Na_(2)CO_(3)`
C. `K_(2)CO_(3)`
D. `Rb_(2)CO_(3)`

Answer

To determine which of the given group-I carbonates has the highest solubility, we can follow these steps:

### Step 1: Identify the Group-I Carbonates
The group-I carbonates we need to consider are:
- Lithium carbonate (Li2CO3)
- Sodium carbonate (Na2CO3)
- Potassium carbonate (K2CO3)
- Rubidium carbonate (Rb2CO3)

### Step 2: Understand the Solubility Trend
In general, the solubility of alkali metal carbonates increases as we move down the group in the periodic table. This is due to the increase in the size of the cation, which leads to a decrease in lattice energy and an increase in solubility.

### Step 3: Analyze Each Carbonate
- **Li2CO3 (Lithium Carbonate)**: This carbonate is known to be relatively insoluble in water due to the small size of the lithium ion, which leads to a stronger lattice energy.
- **Na2CO3 (Sodium Carbonate)**: Sodium carbonate is more soluble than lithium carbonate but less soluble than potassium and rubidium carbonates.
- **K2CO3 (Potassium Carbonate)**: Potassium carbonate has higher solubility compared to lithium and sodium carbonates.
- **Rb2CO3 (Rubidium Carbonate)**: Rubidium carbonate is expected to have the highest solubility among these due to the larger size of the rubidium ion, which results in lower lattice energy.

### Step 4: Conclusion
Based on the trend of increasing solubility down the group, we can conclude that **Rubidium Carbonate (Rb2CO3)** has the highest solubility among the given group-I carbonates.

### Final Answer
The carbonate with the highest solubility among the group-I carbonates is **Rb2CO3 (Rubidium Carbonate)**.

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