Which of the following is not a reducing oxide ?

Options

A. `SO_(2)`
B. `SeO_(2)`
C. TeO
D. `SO_(3)`

Answer

To determine which of the following compounds is not a reducing oxide, we need to analyze the oxidation states of the elements in each compound. Reducing oxides are those that can reduce other substances while being oxidized themselves.

### Step-by-Step Solution:

1. **Identify the Compounds**: The given compounds are SO2, SeO2, TeO, and SO3.

2. **Calculate the Oxidation State of Sulfur in SO2**:
- Let the oxidation state of sulfur (S) be \( X \).
- The oxidation state of oxygen (O) is \(-2\).
- The formula for SO2 gives us:
\[ X + 2(-2) = 0 \implies X - 4 = 0 \implies X = +4 \]
- Since +4 is an intermediate oxidation state, SO2 can act as a reducing oxide.

3. **Calculate the Oxidation State of Selenium in SeO2**:
- Let the oxidation state of selenium (Se) be \( Y \).
- The formula for SeO2 gives us:
\[ Y + 2(-2) = 0 \implies Y - 4 = 0 \implies Y = +4 \]
- +4 is also an intermediate oxidation state, so SeO2 can act as a reducing oxide.

4. **Calculate the Oxidation State of Tellurium in TeO**:
- Let the oxidation state of tellurium (Te) be \( Z \).
- The formula for TeO gives us:
\[ Z + (-2) = 0 \implies Z - 2 = 0 \implies Z = +2 \]
- +2 is an intermediate oxidation state, so TeO can act as a reducing oxide.

5. **Calculate the Oxidation State of Sulfur in SO3**:
- Let the oxidation state of sulfur (S) be \( W \).
- The formula for SO3 gives us:
\[ W + 3(-2) = 0 \implies W - 6 = 0 \implies W = +6 \]
- +6 is the highest oxidation state of sulfur, meaning SO3 cannot be oxidized further and thus cannot act as a reducing oxide.

### Conclusion:
The compound that is not a reducing oxide is **SO3**.