The decreasing valuse of bond angles from `NH_(3) (106^(@))` to `SbH_(3)(101^(@))` down group -15 of the periodic table is due to .

Options

A. decreasing bp-bp repulsion
B. decreasing electronegativity
C. increasing bp-bp repulsion
D. increasing Ip-bp repulsion

Answer

A

Explanation

The bond angle decreases on moving down the group due to decrease in bond pair-bond pair repulsion.
`{:(NH_(3),PH_(3),AsH_(3),SbH_(3),BiH_(3)),(107^(@),94^(@),92^(@),91^(@),90^(@)):}`
This can also be explained by the fact that as the size of central atom increases and its electronegativity decreases. Thus distance between bond pairs of electron increases and bp-bp repulsion decreases. As a result bond angle decreases from `NH_(3)` to `BiH_(3)`