identify the correct statements:

Options

A. Calcium cyanamide on treatment with steam under pressure gives `NH_(3) and CaCO_(3)`
B. `PCl_(5)` is kept in well stopped bottle because it reacts readily with moisture
C. Ammonium nitrite on heating gives ammonia and nitrous acid
D. Cane sugar reacts with conc. `HNO_(3)` to form oxalic acid

Answer

To solve the question of identifying the correct statements among the given options, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: Calcium cyanamide on treatment with steam under pressure gives ammonia and calcium carbonate.**
- **Analysis:** Calcium cyanamide (CaCN2) reacts with steam (H2O) under pressure. The reaction can be represented as:
\[ \text{CaCN}_2 + 2 \text{H}_2\text{O} \rightarrow \text{CaCO}_3 + 2 \text{NH}_3 \]
- **Conclusion:** This statement is **correct**.

2. **Statement 2: PCl5 is kept in a well-stopped bottle because it reacts readily with moisture.**
- **Analysis:** Phosphorus pentachloride (PCl5) reacts with moisture (water) to produce hydrochloric acid (HCl) and phosphoric acid (H3PO4). The reaction is:
\[ \text{PCl}_5 + 4 \text{H}_2\text{O} \rightarrow \text{H}_3\text{PO}_4 + 5 \text{HCl} \]
- **Conclusion:** This statement is **correct**.

3. **Statement 3: Ammonium nitrite on heating gives ammonia and nitrous acid.**
- **Analysis:** Ammonium nitrite (NH4NO2) decomposes upon heating to produce nitrogen gas (N2) and water (H2O):
\[ \text{NH}_4\text{NO}_2 \rightarrow \text{N}_2 + 2 \text{H}_2\text{O} \]
- **Conclusion:** This statement is **incorrect** as it does not produce ammonia and nitrous acid.

4. **Statement 4: Cane sugar reacts with concentrated nitric acid to form oxalic acid.**
- **Analysis:** When cane sugar (C12H22O11) reacts with concentrated nitric acid (HNO3), it can produce oxalic acid (C2H2O4) along with nitrogen dioxide (NO2) and water. The balanced reaction can be represented as:
\[ \text{C}_{12}\text{H}_{22}\text{O}_{11} + 36 \text{HNO}_3 \rightarrow 6 \text{C}_2\text{H}_2\text{O}_4 + 36 \text{NO}_2 + 23 \text{H}_2\text{O} \]
- **Conclusion:** This statement is **correct**.

### Final Conclusion:
The correct statements are **1, 2, and 4**. The only incorrect statement is **3**.