Question

which correctly describes the h - o - h bond angle in a water molecule? a equal to 180° b equal to 109.5° c slightly less than 109.5° d slightly greater than 109.5°

Explanation:

The oxygen atom in a water molecule has a tetrahedral - electron - pair geometry due to two bonding pairs and two lone pairs of electrons. Lone - pair - lone - pair repulsions are stronger than bonding - pair - bonding - pair or lone - pair - bonding - pair repulsions. In a tetrahedral electron - pair geometry with no lone pairs, the bond angle is 109.5°. But in water, the presence of two lone pairs on oxygen compresses the H - O - H bond angle slightly. So the H - O - H bond angle in a water molecule is slightly less than 109.5°.

Answer:

c. slightly less than 109.5°