Which of the following statements are correct about the reaction between the copper metal and dilute `HNO_(3)`?

Options

A. The principle reducing product is `NO` gas
B. `Cu` metal is oxidised to `Cu^(2+)`(aq.) ion which is blue in colour
C. `NO` is paramagnetic and has one unpaired electron in antibonding molecular orbital
D. `NO` reacts with `O_(2)` to produce `NO_(2)` which is linear in shape

Answer

To solve the question regarding the reaction between copper metal and dilute HNO₃, we will analyze each statement provided and determine their correctness based on the chemical principles involved.

### Step-by-Step Solution:

1. **Understanding the Reaction**:
- When copper (Cu) reacts with dilute nitric acid (HNO₃), the products formed are copper(II) nitrate (Cu(NO₃)₂), water (H₂O), and nitrogen oxide (NO). The reaction can be represented as:
\[ \text{Cu} + 2 \text{HNO}_3 \rightarrow \text{Cu(NO}_3\text{)}_2 + \text{H}_2\text{O} + \text{NO} \]

2. **Analyzing Statement 1**:
- "The principal reducing product is NO gas."
- In this reaction, the nitrogen in HNO₃ is reduced from an oxidation state of +5 to +2 (in NO). Therefore, the principal reducing product is indeed NO.
- **Conclusion**: This statement is **correct**.

3. **Analyzing Statement 2**:
- "Copper metal is oxidized to Cu²⁺ aqueous ion which is blue in color."
- Copper metal (Cu) is oxidized to Cu²⁺. However, while Cu²⁺ ions are blue in color, the statement is misleading because it does not specify that the blue color is due to the presence of Cu²⁺ in solution. The statement is technically correct in terms of oxidation but misleading regarding the color.
- **Conclusion**: This statement is **incorrect**.

4. **Analyzing Statement 3**:
- "NO is paramagnetic and has one unpaired electron in anti-bonding molecular orbital."
- According to molecular orbital theory, NO has an unpaired electron, making it paramagnetic. The unpaired electron is indeed in an anti-bonding molecular orbital.
- **Conclusion**: This statement is **correct**.

5. **Analyzing Statement 4**:
- "NO reacts with O₂ to produce NO₂ which is linear in shape."
- NO does react with O₂ to produce NO₂, but NO₂ has a bent or V shape due to the presence of a lone pair on the nitrogen atom, making it not linear.
- **Conclusion**: This statement is **incorrect**.

### Final Answer:
The correct statements about the reaction between copper metal and dilute HNO₃ are:
- Statement 1: The principal reducing product is NO gas. (Correct)
- Statement 3: NO is paramagnetic and has one unpaired electron in anti-bonding molecular orbital. (Correct)