Which of the following oxide is basic ?

Options

A. `CrO`
B. `Cr_(2)O_(3)`
C. `CrO_(3)`
D. `Cr_(2)O_(4)`

Answer

To determine which of the given oxides of chromium is basic, we need to analyze the oxidation states of chromium in each oxide and understand how oxidation states influence basicity.

### Step-by-Step Solution:

1. **Identify the Oxides and Their Formulas**:
The oxides given are:
- CrO
- Cr2O3
- CrO3
- Cr2O4

2. **Determine the Oxidation State of Chromium in Each Oxide**:
- **For CrO**:
- Let the oxidation state of Cr be \( x \).
- The oxidation state of O is \(-2\).
- The equation becomes:
\[ x + (-2) = 0 \implies x = +2 \]
- **For Cr2O3**:
- Let the oxidation state of Cr be \( x \).
- The equation becomes:
\[ 2x + 3(-2) = 0 \implies 2x - 6 = 0 \implies x = +3 \]
- **For CrO3**:
- Let the oxidation state of Cr be \( x \).
- The equation becomes:
\[ x + 3(-2) = 0 \implies x - 6 = 0 \implies x = +6 \]
- **For Cr2O4**:
- Let the oxidation state of Cr be \( x \).
- The equation becomes:
\[ 2x + 4(-2) = 0 \implies 2x - 8 = 0 \implies x = +4 \]

3. **Summarize the Oxidation States**:
- CrO: +2
- Cr2O3: +3
- CrO3: +6
- Cr2O4: +4

4. **Analyze Basicity**:
- Basicity of metal oxides generally increases as the oxidation state of the metal decreases. This is because lower oxidation states correspond to a greater tendency to donate electrons.
- From the oxidation states calculated, CrO has the lowest oxidation state of +2.

5. **Conclusion**:
- Since CrO has the lowest oxidation state (+2), it is the most basic oxide among the given options.

### Final Answer:
The oxide that is basic is **CrO**.

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