Which of the following pair has same structure?

Options

A. `PH _(3) and Cl _(2)`
B. `SO_(2) and NH_(3)`
C. `PCl _(3) and SF_(6)`
D. `NH_(4) ^(+) ans SO_(4) ^(2-)`

Answer

To determine which pair has the same structure, we will analyze the hybridization and molecular geometry of each pair given in the options. We will use the formula for calculating the steric number (SN):

\[ \text{SN} = \frac{1}{2} \left( V + M + \text{Charge (anion)} - \text{Charge (cation)} \right) \]

Where:
- \( V \) = number of valence electrons of the central atom
- \( M \) = number of monovalent atoms attached to the central atom

### Step 1: Analyze the first pair (PH3 and Cl2)

1. **For PH3 (Phosphine)**:
- Central atom: Phosphorus (P)
- Valence electrons (V): 5
- Monovalent atoms (M): 3 (3 Hydrogens)
- Calculation:
\[ \text{SN} = \frac{1}{2} (5 + 3) = \frac{8}{2} = 4 \]
- Bond pairs: 3, Lone pairs: 1 (Shape: Pyramidal)

2. **For Cl2 (Chlorine molecule)**:
- Central atom: Chlorine (Cl)
- Valence electrons (V): 7 (each Cl has 7)
- Monovalent atoms (M): 0
- Calculation:
\[ \text{SN} = \frac{1}{2} (7 + 7) = \frac{14}{2} = 7 \]
- Bond pairs: 1, Lone pairs: 3 (Shape: Linear)

**Conclusion**: PH3 is pyramidal, Cl2 is linear. They do not have the same structure.

### Step 2: Analyze the second pair (SO2 and NH3)

1. **For SO2 (Sulfur Dioxide)**:
- Central atom: Sulfur (S)
- Valence electrons (V): 6
- Monovalent atoms (M): 0 (Oxygen is divalent)
- Calculation:
\[ \text{SN} = \frac{1}{2} (6 + 0) = \frac{6}{2} = 3 \]
- Bond pairs: 2, Lone pairs: 1 (Shape: Bent)

2. **For NH3 (Ammonia)**:
- Central atom: Nitrogen (N)
- Valence electrons (V): 5
- Monovalent atoms (M): 3 (3 Hydrogens)
- Calculation:
\[ \text{SN} = \frac{1}{2} (5 + 3) = \frac{8}{2} = 4 \]
- Bond pairs: 3, Lone pairs: 1 (Shape: Pyramidal)

**Conclusion**: SO2 is bent, NH3 is pyramidal. They do not have the same structure.

### Step 3: Analyze the third pair (PCl3 and SF6)

1. **For PCl3 (Phosphorus Trichloride)**:
- Central atom: Phosphorus (P)
- Valence electrons (V): 5
- Monovalent atoms (M): 3 (3 Chlorines)
- Calculation:
\[ \text{SN} = \frac{1}{2} (5 + 3) = \frac{8}{2} = 4 \]
- Bond pairs: 3, Lone pairs: 1 (Shape: Pyramidal)

2. **For SF6 (Sulfur Hexafluoride)**:
- Central atom: Sulfur (S)
- Valence electrons (V): 6
- Monovalent atoms (M): 6 (6 Fluorines)
- Calculation:
\[ \text{SN} = \frac{1}{2} (6 + 6) = \frac{12}{2} = 6 \]
- Bond pairs: 6, Lone pairs: 0 (Shape: Octahedral)

**Conclusion**: PCl3 is pyramidal, SF6 is octahedral. They do not have the same structure.

### Step 4: Analyze the fourth pair (NH4+ and SO4^2-)

1. **For NH4+ (Ammonium ion)**:
- Central atom: Nitrogen (N)
- Valence electrons (V): 5
- Monovalent atoms (M): 4 (4 Hydrogens)
- Charge: +1 (cation)
- Calculation:
\[ \text{SN} = \frac{1}{2} (5 + 4 - 1) = \frac{8}{2} = 4 \]
- Bond pairs: 4, Lone pairs: 0 (Shape: Tetrahedral)

2. **For SO4^2- (Sulfate ion)**:
- Central atom: Sulfur (S)
- Valence electrons (V): 6
- Monovalent atoms (M): 0 (Oxygen is divalent)
- Charge: -2 (anion)
- Calculation:
\[ \text{SN} = \frac{1}{2} (6 + 0 + 2) = \frac{8}{2} = 4 \]
- Bond pairs: 4, Lone pairs: 0 (Shape: Tetrahedral)

**Conclusion**: Both NH4+ and SO4^2- are tetrahedral. They have the same structure.

### Final Answer:
The pair that has the same structure is **NH4+ and SO4^2-**.

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