H - O - H bond angle in H ₂ O is 104.5^ and not 109^ 28^ because of

Step-by-step solution

The hybridisation of oxygen in water molecule is s p^3 . So, water molecule must be tetrahedral and have bond angle 109^ 28^ . But due to the presence of two lone pair of electrons on oxygen atom (repulsion between lone pair-lone pair) the bond angle decreases about 104.5^ and the geometry becomes distorted tertrahedral or V-shaped.