Select the correct statements about oxygen molecule.

Options

A. It is paramagnetic
B. Its bond order is two
C. Its liquid state it is colourless
D. It has two unpaired electrons

Answer

To determine the correct statements about the oxygen molecule (O2), we will analyze each statement based on the properties of oxygen and its electronic configuration.

### Step 1: Analyze the first statement - "Oxygen is paramagnetic."
1. **Understanding Paramagnetism**: A substance is paramagnetic if it has unpaired electrons in its molecular orbitals.
2. **Electronic Configuration of O2**: The molecular orbital (MO) configuration for O2 is:
- σ1s², σ*1s², σ2s², σ*2s², σ2p_z², π2p_x², π2p_y², π*2p_x¹, π*2p_y¹
3. **Counting Electrons**: O2 has a total of 16 electrons. Filling the MOs, we find that there are two unpaired electrons in the π*2p_x and π*2p_y orbitals.
4. **Conclusion**: Since there are unpaired electrons, O2 is indeed paramagnetic.
- **Result**: This statement is **true**.

### Step 2: Analyze the second statement - "Its bond order is 2."
1. **Calculating Bond Order**: The bond order can be calculated using the formula:
\[ \text{Bond Order} = \frac{(\text{Number of electrons in bonding MOs}) - (\text{Number of electrons in antibonding MOs})}{2} \]
2. **Bonding and Antibonding Electrons**: From the configuration:
- Bonding electrons: 10 (σ1s², σ2s², σ2p_z², π2p_x², π2p_y²)
- Antibonding electrons: 6 (σ*1s², σ*2s², π*2p_x¹, π*2p_y¹)
3. **Plugging into the Formula**:
\[ \text{Bond Order} = \frac{10 - 6}{2} = \frac{4}{2} = 2 \]
4. **Conclusion**: The bond order of O2 is indeed 2.
- **Result**: This statement is **true**.

### Step 3: Analyze the third statement - "Its liquid state is colorless."
1. **Properties of Liquid Oxygen**: Liquid oxygen (O2) is known to have a pale blue color.
2. **Conclusion**: Therefore, the statement that liquid oxygen is colorless is incorrect.
- **Result**: This statement is **false**.

### Step 4: Analyze the fourth statement - "It has two unpaired electrons."
1. **Review of Unpaired Electrons**: As established in Step 1, the electronic configuration shows that O2 has two unpaired electrons in the π* orbitals.
2. **Conclusion**: Thus, the statement about having two unpaired electrons is correct.
- **Result**: This statement is **true**.

### Final Conclusion
The correct statements about the oxygen molecule (O2) are:
1. It is paramagnetic (True).
2. Its bond order is 2 (True).
3. Its liquid state is colorless (False).
4. It has two unpaired electrons (True).

Thus, the correct statements are **1, 2, and 4**.

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