Select the correct option regarding the properties of dioxygen?

Options

A. 1. Dioxygen never reacts with metals.
B. 2. Dioxygen is diamagnetic in nature.
C. 3. Combination of dioxygen with other elements is highly exothermic process.
D. 4. Dioxygen liquefies at 55 K and freezes at 90 K.

Answer

To solve the question regarding the properties of dioxygen, we will analyze each option provided and determine which statements are correct.

### Step-by-Step Solution:

1. **Understanding the Reactivity of Dioxygen:**
- Dioxygen (O2) is known to react with metals. For example, sodium (Na) reacts vigorously with oxygen, which is why sodium is stored under kerosene oil to prevent it from reacting with atmospheric oxygen.
- **Conclusion:** The statement that dioxygen never reacts with metals is incorrect.

2. **Exothermic Nature of Dioxygen Reactions:**
- The combination of dioxygen with other elements, such as in the rusting of iron (Fe + O2 + H2O), is an exothermic reaction. This means it releases heat.
- **Conclusion:** The statement that dioxygen is exothermic is correct.

3. **Molecular Orbital Theory (MOT) and Electron Count:**
- Dioxygen (O2) has a total of 16 electrons (8 from each oxygen atom). According to Molecular Orbital Theory, O2 is paramagnetic because it has two unpaired electrons in its molecular orbital configuration.
- **Conclusion:** The statement that O2 has 16 electrons and is paramagnetic is correct.

4. **Physical Properties of Dioxygen:**
- Dioxygen liquefies at approximately 55 Kelvin and freezes at about 54.36 Kelvin. The statement that it freezes at 90 Kelvin is incorrect.
- **Conclusion:** The statement regarding the freezing point of dioxygen is incorrect.

### Final Evaluation of Options:
- **Option 1:** Incorrect (Dioxygen reacts with metals)
- **Option 2:** Incorrect (O2 is paramagnetic)
- **Option 3:** Correct (Combination with other elements is exothermic)
- **Option 4:** Incorrect (Freezing point is not 90 Kelvin)

### Correct Answer:
The correct option regarding the properties of dioxygen is **Option 3**: The combination of dioxygen with other elements is a highly exothermic process.

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