MnO is :

Options

A. Ferromagnetic
B. Antiferromagnetic
C. Ferrimagnetic
D. Dimagnetic

Answer

To determine the magnetic nature of MnO, we will go through the following steps:

### Step 1: Identify the oxidation state of manganese in MnO
- Manganese (Mn) has an atomic number of 25. In MnO, manganese is in the +2 oxidation state (Mn²⁺), as oxygen (O) typically has a -2 oxidation state.

### Step 2: Determine the electron configuration of Mn²⁺
- The electron configuration of neutral manganese (Mn) is [Ar] 4s² 3d⁵.
- When manganese loses two electrons to form Mn²⁺, it loses the two 4s electrons first, resulting in the configuration [Ar] 3d⁵.

### Step 3: Analyze the d-electron configuration
- The 3d⁵ configuration indicates that there are 5 electrons in the d subshell. This is a half-filled d subshell, which is known to have certain magnetic properties.

### Step 4: Determine the presence of unpaired electrons
- In a half-filled d subshell (3d⁵), all five d electrons are unpaired. This results in a net magnetic moment.

### Step 5: Classify the magnetic behavior
- Since MnO has unpaired electrons, it exhibits paramagnetic behavior. However, we need to consider the crystal structure and interactions in the solid state.
- In the case of MnO, the magnetic interactions between the Mn²⁺ ions lead to antiferromagnetic ordering.

### Step 6: Conclusion
- Therefore, MnO is classified as antiferromagnetic due to the alignment of the spins of the unpaired electrons in opposite directions, resulting in a cancellation of their magnetic moments.

### Final Answer
MnO is **antiferromagnetic**.

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