Which of the following statement(s) is/are incorrect?

Options

A. Sodium bicarbonate is more soluble than sodium carbonate
B. Sodium hydroxide is known as caustic soda
C. Sodium bicarbonate is used as antacid
D. Sodium nitrate is used in the manufacture of soaps

Answer

To determine which of the statements is incorrect, we will analyze each statement one by one.

### Step 1: Analyze the first statement
**Statement:** Sodium bicarbonate is more soluble than sodium carbonate.

- **Explanation:** Sodium bicarbonate (NaHCO₃) has a larger ionic size compared to sodium carbonate (Na₂CO₃). Lattice energy is inversely proportional to the size of the ions; thus, sodium bicarbonate has lower lattice energy, making it more soluble in water than sodium carbonate.
- **Conclusion:** This statement is correct.

**Hint:** Consider the relationship between ionic size and lattice energy when comparing solubility.

### Step 2: Analyze the second statement
**Statement:** Sodium hydroxide is known as caustic soda.

- **Explanation:** Sodium hydroxide (NaOH) is indeed known as caustic soda due to its corrosive nature, which can burn living tissues. The term "caustic" refers to its ability to cause chemical burns.
- **Conclusion:** This statement is correct.

**Hint:** Recall the properties of sodium hydroxide and its common name.

### Step 3: Analyze the third statement
**Statement:** Sodium bicarbonate is used as an antacid.

- **Explanation:** Sodium bicarbonate is a weak base that neutralizes stomach acid (HCl), making it effective as an antacid. It helps relieve heartburn and indigestion.
- **Conclusion:** This statement is correct.

**Hint:** Think about the role of sodium bicarbonate in neutralizing acids.

### Step 4: Analyze the fourth statement
**Statement:** Sodium nitrate is used in the manufacture of soaps.

- **Explanation:** Sodium nitrate (NaNO₃) is primarily used as a preservative and in fertilizers, not in soap manufacturing. Soaps are typically made using sodium hydroxide or potassium hydroxide, not sodium nitrate.
- **Conclusion:** This statement is incorrect.

**Hint:** Identify the common substances used in soap manufacturing and differentiate them from preservatives.

### Final Conclusion
The only incorrect statement among the four provided is the fourth statement: "Sodium nitrate is used in the manufacture of soaps."

### Summary of Incorrect Statements
- **Incorrect Statement:** Sodium nitrate is used in the manufacture of soaps.