Select the compound in which the oxidation number of oxygen is `-1` :-

Options

A. `H_(2)O`
B. `O_(2)F_(2)`
C. `Na_(2)O`
D. `BaO_(2)`

Answer

To determine the compound in which the oxidation number of oxygen is -1, we will analyze each of the given compounds step by step.

### Step 1: Analyze the compounds
We have four compounds to analyze:
1. H2O
2. O2F2
3. Na2O
4. BaO2

### Step 2: Determine the oxidation number of oxygen in each compound

#### Compound 1: H2O
- Hydrogen (H) has an oxidation number of +1.
- Let the oxidation number of oxygen (O) be X.
- The total charge of the molecule is 0.
- The equation will be:
\[ 2(+1) + X = 0 \\ 2 + X = 0 \\ X = -2 \]
- **Oxidation number of oxygen in H2O is -2.**

#### Compound 2: O2F2
- Fluorine (F) has an oxidation number of -1.
- Let the oxidation number of oxygen be X.
- The total charge of the molecule is 0.
- The equation will be:
\[ 2X + 2(-1) = 0 \\ 2X - 2 = 0 \\ 2X = 2 \\ X = +1 \]
- **Oxidation number of oxygen in O2F2 is +1.**

#### Compound 3: Na2O
- Sodium (Na) has an oxidation number of +1.
- Let the oxidation number of oxygen be X.
- The total charge of the molecule is 0.
- The equation will be:
\[ 2(+1) + X = 0 \\ 2 + X = 0 \\ X = -2 \]
- **Oxidation number of oxygen in Na2O is -2.**

#### Compound 4: BaO2
- Barium (Ba) has an oxidation number of +2.
- Let the oxidation number of oxygen be X.
- The total charge of the molecule is 0.
- The equation will be:
\[ 1(+2) + 2X = 0 \\ 2 + 2X = 0 \\ 2X = -2 \\ X = -1 \]
- **Oxidation number of oxygen in BaO2 is -1.**

### Step 3: Conclusion
From our analysis, we find that the oxidation number of oxygen is -1 in **BaO2**.

### Final Answer:
The compound in which the oxidation number of oxygen is -1 is **BaO2**.

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