Which statement describes a polar molecule?

• A. It has uniform charge distribution
• B. It is hydrophobic
• C. It has distinct positive and negative ends
• D. It lacks solubility in water

Answer: (C)

A polar molecule is characterized by having distinct positive and negative ends, which results from an unequal distribution of electrons between atoms with different electronegativities. This uneven distribution creates a dipole moment where one part of the molecule has a slight positive charge while another part has a slight negative charge. This polarity is what allows polar molecules to interact with other polar substances, including water, through hydrogen bonding and other types of intermolecular forces.

In contrast to the concepts of uniform charge distribution, hydrophobicity, and lack of solubility in water, which are typical of nonpolar molecules, a polar molecule's unique structure makes it soluble in polar solvents like water. This solubility is crucial for many biological processes where polar molecules, such as sugars and proteins, dissolve and interact within aqueous environments. Thus, the statement about having distinct positive and negative ends effectively captures the essence of a polar molecule's behavior and characteristics.