Which of the following species has polar and non-polar bonds but molecule as a whole is non-plonar?

Options

A. `S_(2)O_(3)^(2-)`
B. `(SCN)_(2)`
C. `Be_(2)Cl_(4)`
D. `Si_(2)H_(6)`

Explanation

To solve the question of which species has both polar and non-polar bonds but is non-polar as a whole, we will analyze the given compounds step by step.

### Step 1: Analyze the Compounds
We need to evaluate the structures of the following compounds:
1. \( \text{S}_2\text{O}_3^{2-} \)
2. \( \text{SCN} \)
3. \( \text{BeCl}_2 \)
4. \( \text{Si}_2\text{H}_6 \)

### Step 2: Draw and Analyze \( \text{S}_2\text{O}_3^{2-} \)
- The structure consists of two sulfur atoms and three oxygen atoms.
- The S-S bonds are non-polar (same electronegativity).
- The S-O bonds are polar (oxygen is more electronegative).
- The overall dipole moment is non-zero due to the polar bonds, making the molecule polar.

**Conclusion:** \( \text{S}_2\text{O}_3^{2-} \) is not the answer.

### Step 3: Draw and Analyze \( \text{SCN} \)
- The structure consists of sulfur, carbon, and nitrogen.
- The S-S bond is non-polar (same electronegativity).
- The C-N bond is polar (nitrogen is more electronegative).
- The overall dipole moment is non-zero, making the molecule polar.

**Conclusion:** \( \text{SCN} \) is not the answer.

### Step 4: Draw and Analyze \( \text{BeCl}_2 \)
- The structure consists of beryllium and two chlorine atoms.
- All Be-Cl bonds are polar (chlorine is more electronegative).
- The molecule has a linear shape, and the dipole moments cancel each other out, resulting in a non-polar molecule.

**Conclusion:** \( \text{BeCl}_2 \) has all polar bonds and is non-polar as a whole, but it does not meet the criteria of having both polar and non-polar bonds.

### Step 5: Draw and Analyze \( \text{Si}_2\text{H}_6 \)
- The structure consists of two silicon atoms and six hydrogen atoms.
- The Si-Si bond is non-polar (same electronegativity).
- The Si-H bonds are polar (silicon is less electronegative than hydrogen).
- The overall dipole moment cancels out due to the symmetrical arrangement, making the molecule non-polar.

**Conclusion:** \( \text{Si}_2\text{H}_6 \) has both polar (Si-H) and non-polar (Si-Si) bonds, and the molecule as a whole is non-polar.

### Final Answer
The species that has polar and non-polar bonds but is non-polar as a whole is **\( \text{Si}_2\text{H}_6 \)**.

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