Which of following is a polar molecule 1) KCl 2) F – F (3) H-O-H (4) S8
The correct answer and explanation is:
Correct Answer: (3) H–O–H
A polar molecule is one that has a net dipole moment due to unequal sharing of electrons between atoms with different electronegativities and an asymmetric molecular shape.
H–O–H (Water) is a polar molecule. Oxygen is much more electronegative than hydrogen, which causes the electrons in the O–H bonds to be pulled closer to the oxygen atom. Additionally, water has a bent molecular geometry with an angle of about 104.5°, not a straight line. This asymmetry ensures that the dipoles from the two O–H bonds do not cancel out, giving the molecule an overall dipole moment. Therefore, water is a classic example of a polar molecule.
KCl (Potassium Chloride) is not a polar molecule; it is an ionic compound. It consists of a metal (potassium) and a non-metal (chlorine). Electrons are transferred, not shared, between the atoms, resulting in full positive and negative charges. Although the bond is highly polar, the compound as a whole is not considered a polar molecule because it forms a lattice structure typical of salts.
F–F (Fluorine gas) is a nonpolar molecule. It consists of two identical fluorine atoms sharing electrons equally. Because there is no difference in electronegativity, there is no dipole moment, and the molecule is completely nonpolar.
S₈ (Sulfur octamer) is also nonpolar. It has a symmetrical ring structure made up of identical sulfur atoms. The electrons are shared equally, and the molecule has no net dipole moment.
In conclusion, among the given options, only H–O–H meets the requirements for being a polar molecule due to its bond polarity and molecular geometry. It has an uneven charge distribution, making it polar.