Question

why the bond angle of water is not 109.5 like that of methane​

Answer 1

Answer:

The H—C—H bond angle in methane is the tetrahedral angle, 109.5°. This angle is obtained when all four pairs of outer electrons repel each other equally. The bond angles in ammonia and in water are less than 109.5° because of the stronger repulsion by their lone pairs of electrons.

Explanation:

Answer 2

Answer:

since the repulsion force between lone pair and lone pair dominates it pushes the bond pair due to which the bond angle in water decrease because of the presence of 2lone pair and 2bond pair which is not seen in methane because of the presence of all 4 bond pairs

Explanation:

Since the repulsion force follows the trend given below------

Lone pair-Lone pair > Lone pair-Bond pair > Bond pair-Bond pair