Which of the following best explains why water (H_2O) is a polar molecule?

• A. Water has a linear molecular geometry, causing the dipole moments to cancel.
• B. Water molecules have no difference in electronegativity between their atoms.
• C. Water has a bent molecular geometry and a significant difference in electronegativity between hydrogen and oxygen, resulting in a net dipole moment.
• D. Water is composed of two identical atoms, so the bond dipoles cancel each other out.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the concept of molecular polarity, which depends on both the difference in electronegativity between atoms and the shape (geometry) of the molecule.
2. Step 2: Recognize that water (H\_2O) consists of oxygen and hydrogen atoms, which have a significant difference in electronegativity, meaning the O-H bonds are polar.
3. Step 3: Identify the molecular geometry of water, which is bent (angular) due to the two lone pairs on oxygen, not linear.
4. Step 4: Realize that because of the bent shape, the individual bond dipole moments do not cancel out but instead combine to create a net dipole moment.
5. Step 5: Conclude that the combination of bent geometry and electronegativity difference results in water being a polar molecule.