Which of the following is a true peroxide ?

Options

A. `PbO_2`
B. `CO_2`
C. `SO_2`
D. `BaO_2`

Answer

To determine which of the given compounds is a true peroxide, we need to identify the oxidation state of the oxygen in each compound. A true peroxide is characterized by the presence of the peroxide ion (O2^2-), where each oxygen has an oxidation state of -1.

Let's analyze the compounds one by one:

1. **Lead(IV) oxide (PbO2)**:
- Lead (Pb) has an oxidation state of +4.
- Let the oxidation state of oxygen be x.
- The equation can be set up as follows:
\[ +4 + 2x = 0 \]
- Solving for x:
\[ 2x = -4 \implies x = -2 \]
- Therefore, the oxidation state of oxygen in PbO2 is -2, which means it is not a true peroxide.

2. **Lead(II) oxide (PbO)**:
- Lead (Pb) has an oxidation state of +2.
- The equation can be set up as follows:
\[ +2 + x = 0 \]
- Solving for x:
\[ x = -2 \]
- Therefore, the oxidation state of oxygen in PbO is -2, which means it is not a true peroxide.

3. **Barium peroxide (BaO2)**:
- Barium (Ba) has an oxidation state of +2.
- Let the oxidation state of oxygen be x.
- The equation can be set up as follows:
\[ +2 + 2x = 0 \]
- Solving for x:
\[ 2x = -2 \implies x = -1 \]
- Therefore, the oxidation state of oxygen in BaO2 is -1, which indicates that it is a true peroxide.

4. **Sodium peroxide (Na2O2)**:
- Sodium (Na) has an oxidation state of +1.
- Let the oxidation state of oxygen be x.
- The equation can be set up as follows:
\[ 2(+1) + 2x = 0 \]
- Solving for x:
\[ 2 + 2x = 0 \implies 2x = -2 \implies x = -1 \]
- Therefore, the oxidation state of oxygen in Na2O2 is -1, which also indicates that it is a true peroxide.

After analyzing all options, we find that both Barium peroxide (BaO2) and Sodium peroxide (Na2O2) are true peroxides. However, since the question asks for a single answer, we can conclude that:

**The true peroxide is BaO2 (Barium peroxide).**