Which factor is primarily responsible for the bent molecular geometry of a water (H_2O) molecule?

• A. The absence of lone pairs on the oxygen atom
• B. The presence of two lone pairs of electrons on the oxygen atom
• C. The equal sharing of electrons between hydrogen and oxygen atoms
• D. The linear arrangement of hydrogen atoms around the oxygen atom

Answer: (B)

Verified step by step guidance

1. Identify the central atom in the water molecule, which is oxygen, and note that it has two hydrogen atoms bonded to it.
2. Recall that the molecular geometry depends on both bonding pairs and lone pairs of electrons around the central atom, according to the VSEPR (Valence Shell Electron Pair Repulsion) theory.
3. Recognize that oxygen has two lone pairs of electrons in addition to the two bonding pairs with hydrogen atoms.
4. Understand that lone pairs repel more strongly than bonding pairs, causing the bonded hydrogen atoms to be pushed closer together, resulting in a bent shape rather than a linear one.
5. Conclude that the primary factor responsible for the bent molecular geometry of water is the presence of two lone pairs of electrons on the oxygen atom.