Question
Consider the molecules $$C{H_4},N{H_3}$$ and $${H_2}O.$$
Which of the given statements is false?
A.
The $$H-O-H$$ bond angle in $${H_2}O$$ is larger than the $$H - C - H$$ bond angle in $$C{H_4}$$
B.
The $$H - O - H$$ bond angle in $${H_2}O$$ is smaller than the $$H - N - H$$ bond angle in $$N{H_3}$$
C.
The $$H - C - H$$ bond angle in $$C{H_4}$$ is larger than the $$H - N - H$$ bond angle in $$N{H_3}$$
D.
The $$H - C - H$$ bond angle in $$C{H_4},$$ the $$H - N - H$$ bond angle in $$N{H_3}$$ and the $$H - O - H$$ bond angle in $${H_2}O$$ are all greater than $${90^ \circ }$$
Answer :
The $$H-O-H$$ bond angle in $${H_2}O$$ is larger than the $$H - C - H$$ bond angle in $$C{H_4}$$
Solution :
As the number of lone pair of electrons on central element increases, repulsion between those lone pair of electrons increases and therefore, bond angle decreases.
Molecules Bond angle
$$C{H_4}$$ ( no lone pair of electrons ) $${109.5^ \circ }$$
$$N{H_3}$$ ( one lone pair of electrons ) $${107.5^ \circ }$$
$${H_2}O$$ ( two lone pair of electrons ) $${104.45^ \circ }$$