Question

The correct order of bond angles of the molecules \( SiCl_4 \), \( SO_3 \), \( NH_3 \), \( HgCl_2 \) is:

• A. \( SO_3 > SiCl_4 > NH_3 > HgCl_2 \)
• B. \( SiCl_4 > NH_3 > HgCl_2 > SO_3 \)
• C. \( HgCl_2 > SO_3 > NH_3 > SiCl_4 \)
• D. \( HgCl_2 > SO_3 > SiCl_4 > NH_3 \)

Hint:

Bond angles depend on molecular geometry and hybridization. Linear molecules (sp) have 180°, trigonal planar (sp²) have 120°, tetrahedral (sp³) have 109.5°, and lone pairs reduce bond angles further.

Answer 1

The Correct Option is D

The problem requires determining the correct order of bond angles for the molecules \( SiCl_4 \), \( SO_3 \), \( NH_3 \), and \( HgCl_2 \). To resolve this, we must understand the molecular geometry and associated bond angles for each molecule:

\(SiCl_4\): Silicon tetrachloride adopts a tetrahedral geometry, giving it bond angles of 109.5°.

\(SO_3\): Sulfur trioxide has a trigonal planar shape, with bond angles of 120°. 

\(NH_3\): Ammonia exhibits a trigonal pyramidal shape due to a lone pair, resulting in a bond angle of approximately 107°.

\(HgCl_2\): Mercury(II) chloride forms a linear structure, which leads to bond angles of 180°.

Given these geometries, the order from largest to smallest bond angles is:

• \(HgCl_2\) (180°)
• \(SO_3\) (120°)
• \(SiCl_4\) (109.5°)
• \(NH_3\) (107°)

Thus, the correct order is: \(HgCl_2 > SO_3 > SiCl_4 > NH_3\).

Answer 2

To determine the bond angles of the given molecules, we need to consider the shape of the molecule and the factors that affect bond angles such as lone pairs and electron pairs.

1. SO₃ (Sulfur Trioxide):

SO₃ has a trigonal planar shape with no lone pairs on the central atom, which gives a bond angle of 120°.

2. SiCl₄ (Silicon Tetrachloride):

SiCl₄ has a tetrahedral shape with bond angles of 109.5° because it has four bonding pairs and no lone pairs on the central atom.

3. NH₃ (Ammonia):

NH₃ has a trigonal pyramidal shape with bond angles of 107° because it has three bonding pairs and one lone pair on the nitrogen atom, which reduces the bond angle.

4. HgCl₂ (Mercury(II) chloride):

HgCl₂ has a linear shape with bond angles of 180°, as it involves two bonding pairs and no lone pairs around the central atom.

Conclusion:

Based on the bond angles, the correct order is:

HgCl₂ (180°) > SO₃ (120°) > SiCl₄ (109.5°) > NH₃ (107°)