Which of the following statements is correct?

Options

A. Sodium carbonate decomposes on heating
B. sodium biarbonate is more soluble in water than potassium bicarbonate.
C. sodium when heated with excess of `O_(2)`, gives peroxide
D. Lithium halides are highly ionic in nature.

Explanation

To determine which of the given statements is correct, let's analyze each option step by step:

### Step 1: Analyze Option A
**Statement:** Sodium carbonate decomposes on heating.

**Analysis:** This statement is incorrect. Sodium carbonate (Na2CO3) does not decompose upon heating. Instead, it remains stable under heat. On the other hand, lithium carbonate (Li2CO3) does decompose when heated.

**Conclusion for Option A:** Incorrect.

### Step 2: Analyze Option B
**Statement:** Sodium bicarbonate is more soluble in water than potassium bicarbonate.

**Analysis:** This statement is also incorrect. Potassium bicarbonate (KHCO3) is more soluble in water than sodium bicarbonate (NaHCO3). Sodium bicarbonate has limited solubility and can form a precipitate in certain conditions.

**Conclusion for Option B:** Incorrect.

### Step 3: Analyze Option C
**Statement:** Sodium when heated with excess of O2 gives peroxide.

**Analysis:** This statement is correct. When sodium (Na) is heated in the presence of excess oxygen (O2), it forms sodium peroxide (Na2O2). The balanced reaction can be represented as:
\[ 2Na + O2 \rightarrow Na2O2 \]

**Conclusion for Option C:** Correct.

### Step 4: Analyze Option D
**Statement:** Lithium halides are highly ionic in nature.

**Analysis:** This statement is incorrect. While most alkali metal halides are ionic, lithium halides (LiX) exhibit significant covalent character due to the small size and high charge density of lithium ions. This results in a higher degree of covalent character compared to other alkali metal halides.

**Conclusion for Option D:** Incorrect.

### Final Conclusion
After analyzing all the options, the only correct statement is **Option C**: Sodium when heated with excess of O2 gives peroxide.

---