In which of the following species the interatomic bond angle is `109^(@)28'` ?

Options

A. `NH_4^(+),(BF_4)^(-1)`
B. `(NH_4)^(+),BF_3`
C. `NH_3,BF_4`
D. `(NH_2)^(-1),BF_3`

Answer

A

Explanation

`NH_4^(+)`
`H=1/2(5+4-1+0)=4`

`rArrsp^3` hybridization with no lone pair and tetrahedral geometry. Bond angles are 109°28.
`BF_4^(-)`:
`H=1/2(3+4-0+1)=4`
`rArrsp^3` hybridization with no lone pair and tetrahedral geometry. Bond angles are 109°28..