Which of the following statements are correct? a. HF and H2O are polar molecules. b. CH4 and CO2 are non-polar molecules. c. CO2 and SO2 are non-polar molecules.

Which of the following statements are correct? a. HF and H2O are polar molecules. b. CH4 and CO2 are non-polar molecules. c. CO2 and SO2 are non-polar molecules. Correct Answer a and b

The correct answer is a and b.

Key Points

Analysis of all the 3 statements:

Statement a. HF and H2O are polar molecules​

• H−F and H-O bonds are polar due to the high electronegativity of fluorine and oxygen respectively.
• Hence HF and H₂O are polar molecules.
• Hence a is correct

Statement b. CH4 and CO2 are non-polar molecules

• There is a small difference in electronegativity between the Carbon and Hydrogen bonds.
• Thus, there is no net (overall) polarity.
• That makes CH4 a nonpolar molecule.
• CO2 is a linear molecule so the resultant dipole moment is zero
• Since the individual dipole moments of CO bond cancel each other. 
• That makes CO2 a polar molecule.
• Hence b is correct

Statement c. CO2 and SO2 are non-polar molecules

• ​CO₂ is a linear molecule, so the resultant dipole moment is zero.
• Since the individual dipole moments of CO bond cancel each other.
• Whereas, SO₂ is an angular molecule due to which it has a net dipole moment.
• Therefore SO₂ is polar and CO₂ is non-polar.
• Hence c is not correct.​

Important Points

• Polar Molecules
  • They produce the strongest force and forms H bonds or dipole-dipole bonds. 
  • Polar molecules interact with other polar substances. 
  • These molecules have positive and negative charges on the opposite ends when the more electronegative atom tries to pull electrons towards itself than the less electronegative atom.
  • Such bonds are known as a polar covalent molecule or simply polar molecule.
  • Therefore, they are electrically charged. Example: Sulphur, etc

[ alt="polar" src="//storage.googleapis.com/tb-img/production/20/12/polar.png" style="width: 280px; height: 133px;">

• Nonpolar Molecules
  • They produce the weakest force and forms Van Der Waal interactions between nonpolar bonds.
  • Nonpolar molecules do not interact with other nonpolar substances.
  • Does not have a large number of charges at opposite ends.
  • Example: Carbon dioxide, etc.