The correct sequence of thermal stability of the following carbonates is:

Options

A. `MgCO_(3) lt CaCO_(3) lt SrCO_(3) lt BaCO_(3)`
B. `MgCO_(3) lt SrCO_(3) lt CaCO_(3) lt BaCO_(3)`
C. `BaCO_(3) lt SrCO_(3) lt CaCO_(3)lt MgCO_(3)`
D. `BaCO_(3) lt CaCO_(3) lt SrCO_(3) lt MgCO_(3)`

Explanation

To determine the correct sequence of thermal stability of the given carbonates, we need to consider the properties of alkaline earth metal carbonates. Here’s a step-by-step solution:

### Step 1: Understand Thermal Stability
Thermal stability refers to the ability of a compound to withstand high temperatures without decomposing. In the context of carbonates, we are interested in how resistant they are to decomposition when heated.

**Hint:** Remember that thermal stability increases with the ability of the compound to resist decomposition.

### Step 2: Identify the Group
The carbonates in question belong to the alkaline earth metals, which include magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). These metals are located in Group 2 of the periodic table.

**Hint:** Focus on the group trends in the periodic table, especially for alkaline earth metals.

### Step 3: Analyze the Trend
As we move down the group from magnesium to barium, the size of the metal cation increases. This increase in size affects the thermal stability of the carbonates:

- **Magnesium Carbonate (MgCO₃)**: Small cation, higher polarizing power, less stable.
- **Calcium Carbonate (CaCO₃)**: Larger cation than Mg, more stable than MgCO₃.
- **Strontium Carbonate (SrCO₃)**: Even larger cation, more stable than CaCO₃.
- **Barium Carbonate (BaCO₃)**: Largest cation, most stable among the four.

**Hint:** Remember that larger cations generally lead to greater thermal stability due to lower polarizing power.

### Step 4: Establish the Sequence
Based on the analysis, the thermal stability of the carbonates increases as we move down the group. Therefore, the order of thermal stability from least stable to most stable is:

1. Magnesium Carbonate (MgCO₃)
2. Calcium Carbonate (CaCO₃)
3. Strontium Carbonate (SrCO₃)
4. Barium Carbonate (BaCO₃)

**Hint:** Write down the carbonates in order of increasing size of the cation to visualize the trend.

### Final Answer
The correct sequence of thermal stability of the carbonates is:
**MgCO₃ < CaCO₃ < SrCO₃ < BaCO₃**