Which molecule represent by the bold atoms are in their lowest oxidation state?

Options

A. `F_(2)O`
B. `H_(2)S`
C. `PH_(3)`
D. `N_(2)H_(4)`

Explanation

To determine which bold atom in the given molecules is in its lowest oxidation state, we will analyze the oxidation states of the bolded atoms in each molecule: F2O, H2S, PH3, and N2H4.

### Step 1: Analyze F2O
- **Bold Atom**: Oxygen (O)
- **Oxidation State Calculation**:
- Let the oxidation state of oxygen be \( x \).
- Fluorine has an oxidation state of -1. Since there are 2 fluorine atoms, the equation becomes:
\[ x + 2(-1) = 0 \implies x - 2 = 0 \implies x = +2 \]
- **Conclusion**: The oxidation state of oxygen in F2O is +2, which is not the lowest oxidation state.

### Step 2: Analyze H2S
- **Bold Atom**: Sulfur (S)
- **Oxidation State Calculation**:
- Let the oxidation state of sulfur be \( y \).
- Hydrogen has an oxidation state of +1. Since there are 2 hydrogen atoms, the equation becomes:
\[ y + 2(+1) = 0 \implies y + 2 = 0 \implies y = -2 \]
- **Conclusion**: The oxidation state of sulfur in H2S is -2, which is the lowest oxidation state for sulfur.

### Step 3: Analyze PH3
- **Bold Atom**: Phosphorus (P)
- **Oxidation State Calculation**:
- Let the oxidation state of phosphorus be \( z \).
- Hydrogen has an oxidation state of +1. Since there are 3 hydrogen atoms, the equation becomes:
\[ z + 3(+1) = 0 \implies z + 3 = 0 \implies z = -3 \]
- **Conclusion**: The oxidation state of phosphorus in PH3 is -3, which is the lowest oxidation state for phosphorus.

### Step 4: Analyze N2H4
- **Bold Atom**: Nitrogen (N)
- **Oxidation State Calculation**:
- Let the oxidation state of nitrogen be \( A \).
- Hydrogen has an oxidation state of +1. Since there are 4 hydrogen atoms, the equation becomes:
\[ 2A + 4(+1) = 0 \implies 2A + 4 = 0 \implies 2A = -4 \implies A = -2 \]
- **Conclusion**: The oxidation state of nitrogen in N2H4 is -2, which is not the lowest oxidation state for nitrogen.

### Final Conclusion
- The bold atom in **H2S (sulfur)** is in its lowest oxidation state of -2.
- The bold atom in **PH3 (phosphorus)** is also in its lowest oxidation state of -3.

### Summary of Lowest Oxidation States:
- **H2S**: Sulfur (-2)
- **PH3**: Phosphorus (-3)