Question

which statement explains why hydrogen bonds are able to form between water molecules?

• water molecules are polar.
• water molecule atoms have weak atomic bonds..
• water molecules show adhesion.
• water molecules are large.

Explanation:

To determine why hydrogen bonds form between water molecules, we analyze each option:

• "Water molecules are polar": A water molecule ($\ce{H_2O}$) has a bent shape, with oxygen being more electronegative than hydrogen. This creates a partial negative charge on oxygen and partial positive charges on hydrogens, making the molecule polar. Polar molecules can form hydrogen bonds (a type of intermolecular force) between the partial positive H of one water molecule and the partial negative O of another.
• "Water molecule atoms have weak atomic bonds": The covalent bonds within a water molecule (between H and O) are strong, not weak. This option is incorrect.
• "Water molecules show adhesion": Adhesion is the attraction between water and other substances, not the reason for hydrogen bonding between water molecules. This is a result of hydrogen bonding, not the cause.
• "Water molecules are large": Water molecules are relatively small (molar mass ~18 g/mol). Size is not related to hydrogen bond formation between them.

So the correct statement is that water molecules are polar.

Answer:

A. Water molecules are polar.