Water is known as a polar molecule because:

• A. its molecular geometry is linear
• B. it contains equal numbers of protons and neutrons
• C. it forms ionic bonds between hydrogen and oxygen
• D. it has an uneven distribution of electron density, resulting in a partial positive charge on hydrogen atoms and a partial negative charge on the oxygen atom

Answer: (D)

Verified step by step guidance

1. Understand the concept of molecular polarity: A molecule is polar if it has an uneven distribution of electron density, leading to partial positive and negative charges within the molecule.
2. Recall the molecular geometry of water: Water (H\_2O) has a bent (angular) shape, not linear, due to the two lone pairs on oxygen that repel the hydrogen atoms.
3. Recognize the type of bonding in water: Water molecules are held together by covalent bonds between hydrogen and oxygen atoms, not ionic bonds.
4. Analyze the electronegativity difference: Oxygen is more electronegative than hydrogen, so it attracts the shared electrons more strongly, creating a partial negative charge on oxygen and partial positive charges on hydrogens.
5. Conclude that the uneven electron distribution and bent shape cause water to be a polar molecule, which explains its unique properties.