Question

Identify the number of molecules having permanent dipole moment from the following: \[ CCl_4, NF_3, H_2S, HBr, SF_4, SiF_4, XeF_4, BeCl_2, SnCl_2, BrF_5, SO_2 \]

• A. \(5\)
• B. \(7\)
• C. \(6\)
• D. \(6\)

Hint:

A molecule is polar if it has an asymmetrical shape and polar bonds. Check molecular geometry and electronegativity differences to determine dipole moment.

Answer 1

The Correct Option is B

Step 1: Understanding Dipole Moment A molecule has a permanent dipole moment if: 
- It has polar bonds due to electronegativity differences. 
- The molecule has an asymmetrical shape, leading to a net dipole moment. 

Step 2: Analyzing the Given Molecules 
- Nonpolar Molecules (No Dipole Moment): 
- \( CCl_4 \) (tetrahedral, symmetrical) 
- \( SiF_4 \) (tetrahedral, symmetrical) 
- \( XeF_4 \) (square planar, symmetrical) 
- \( BeCl_2 \) (linear, symmetrical) 
- Polar Molecules (Have Dipole Moment): 
- \( NF_3 \) (trigonal pyramidal, asymmetric) 
- \( H_2S \) (bent, asymmetric) 
- \( HBr \) (linear, polar bond) 
- \( SF_4 \) (see
-saw shape, asymmetric) 
- \( SnCl_2 \) (bent, asymmetric) 
- \( BrF_5 \) (square pyramidal, asymmetric) 
- \( SO_2 \) (bent, asymmetric) 

Step 3: Counting Molecules with Dipole Moment Polar molecules: \[ NF_3, H_2S, HBr, SF_4, SnCl_2, BrF_5, SO_2 \] Total = 7 molecules. Thus, the correct answer is \( \mathbf{(2)} \ 7 \).