Question

$\text{The number of non-polar molecules from the following is \_\_\_\_\_\_.} \\ \text{HF, H}_2\text{O, SO}_2, \, \text{H}_2, \, \text{CO}_2, \, \text{CH}_4, \, \text{NH}_3, \, \text{HCl, CHCl}_3, \, \text{BF}_3$

Answer 1

Correct Answer: 4

The problem requires identifying non-polar molecules from a given list. A molecule is non-polar when its net dipole moment is zero, often due to a symmetrical arrangement of polar bonds that cancel each other out. 
 

• HF: Polar due to significant electronegativity difference between H and F.
• H₂O: Polar because of its bent shape, causing a net dipole moment.
• SO₂: Polar, also due to its bent shape.
• H₂: Non-polar, as identical atoms share electrons equally.
• CO₂: Non-polar; although it has polar bonds, the linear geometry cancels the dipoles.
• CH₄: Non-polar; tetrahedral symmetry allows dipoles to cancel.
• NH₃: Polar due to its trigonal pyramidal shape.
• HCl: Polar due to electronegative difference.
• CHCl₃: Polar; asymmetric molecule leads to a net dipole.
• BF₃: Non-polar; trigonal planar symmetry results in dipole cancellation.

Counting non-polar molecules, we have H₂, CO₂, CH₄, and BF₃. Hence, there are 4 non-polar molecules. 

Answer 2

Non-polar molecules have a symmetrical arrangement of atoms that results in no net dipole moment. In the given list: - \(CO_2\) is linear and symmetrical, so it is non-polar. - \(H_2\) is diatomic and non-polar because it is composed of identical atoms. - \(CH_4\) has a tetrahedral geometry with symmetrical bond distribution, making it non-polar. - \(BF_3\) has a trigonal planar geometry, which is symmetrical and therefore non-polar. 
Other molecules like HF, \(H_2O\), \(SO_2\), \(NH_3\), HCl, and \(CHCl_3\) are polar due to their asymmetrical shapes or differences in electronegativity. Therefore, there are four non-polar molecules in the list.
The Correct answer is: 4