why does the presence of lone pair electrons contribute to the polarity of a water molecule?\n○ they allow…

why does the presence of lone pair electrons contribute to the polarity of a water molecule?\n○ they allow the bonds between oxygen and hydrogen to be single.\n○ they increase the partial positive charge on the oxygen atom.\n○ they prevent the atoms from forming a linear molecule.\n○ they counter the uneven pull on electrons between the atoms.

why does the presence of lone pair electrons contribute to the polarity of a water molecule?\n○ they allow the bonds between oxygen and hydrogen to be single.\n○ they increase the partial positive charge on the oxygen atom.\n○ they prevent the atoms from forming a linear molecule.\n○ they counter the uneven pull on electrons between the atoms.

Answer

Brief Explanations:

To determine the correct answer, we analyze each option:

  • Option 1: The type of bond (single) between O and H in water is due to electron sharing, not lone pairs. Lone pairs don't determine bond type here, so this is incorrect.
  • Option 2: Oxygen is more electronegative than hydrogen, so oxygen has a partial negative charge (not positive) in water. Lone pairs don't increase a positive charge on O, so this is incorrect.
  • Option 3: In a water molecule ((H_2O)), the oxygen atom has two lone pairs of electrons. These lone pairs, along with the two bonding pairs (to hydrogen), cause the molecule to adopt a bent (angular) shape (due to electron - pair repulsion, following VSEPR theory) instead of a linear shape. A linear molecule would have symmetric charge distribution, but the bent shape leads to an asymmetric distribution of charge, contributing to polarity. This option is correct.
  • Option 4: Lone pairs do not counter the uneven pull of electrons (which is due to electronegativity differences). The uneven pull (polarity of O - H bonds) and the molecular shape (influenced by lone pairs) together contribute to molecular polarity. Lone pairs don't counter the electronegativity - driven electron pull, so this is incorrect.

Answer:

C. They prevent the atoms from forming a linear molecule.