Which of the following compounds is metallic and ferromagnetic ?

Options

A. `CrO_(2)`
B. `VO_(2)`
C. `MnO_(2)`
D. `TiO_(2)`

Answer

To determine which of the given compounds is metallic and ferromagnetic, we will analyze each compound based on its oxidation state and the properties of the elements involved.

### Step 1: Identify the oxidation states of each compound.
- **CrO2**: Chromium (Cr) has an oxidation state of +4.
- **VO2**: Vanadium (V) also has an oxidation state of +4.
- **MnO2**: Manganese (Mn) has an oxidation state of +4.
- **TiO2**: Titanium (Ti) has an oxidation state of +4.

### Step 2: Determine the metallic nature of the compounds.
- **Metallic Compounds**: Metallic compounds typically consist of metals. Among the elements chromium, vanadium, manganese, and titanium, chromium (Cr) and vanadium (V) are known to be metals. Manganese is also a metal, while titanium is a transition metal.

### Step 3: Check for ferromagnetic properties.
- **Ferromagnetism**: Ferromagnetism is a property exhibited by certain metals, notably iron (Fe), cobalt (Co), and nickel (Ni). However, chromium is also known to exhibit ferromagnetic properties under certain conditions.
- **CrO2**: Chromium in the +4 oxidation state can exhibit ferromagnetism.
- **VO2**: Vanadium does not exhibit ferromagnetism.
- **MnO2**: Manganese in the +4 oxidation state does not exhibit ferromagnetism.
- **TiO2**: Titanium does not exhibit ferromagnetism.

### Step 4: Conclusion
Among the compounds listed, **CrO2** is the only compound that is both metallic (due to the presence of chromium) and ferromagnetic (due to chromium's ability to exhibit ferromagnetism).

### Final Answer
**CrO2** is the compound that is metallic and ferromagnetic.

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