The correct order of bond angles of the given compounds is

Options

A. `NH_(3)lt PH_(3)lt AsH_(3)lt SbH_(3)`
B. `"SbH"_(3)lt"AsH"_(3)lt"PH"_(3)lt"NH"_(3)`
C. `"NH"_(3)lt"AsH"_(3)lt"SbH"_(3)lt"PH"_(3)`
D. `"PH"_(3)lt"SbH"_(3)lt"AsH"_(3)lt"NH"_(3)`

Answer

B

Explanation

As we move down the group electronegativity decreases resulting in decrease of electron density. This results decrease in repulsive interactions between the bonded electron pairs hence, H-M-H bond angle reduces. The correct order of decreasing bond angle is
`H-M-H" NH"_(3)gt PH_(3)gt "AsH"_(3)gt "SbH"_(3)`
Bond angle `107^(@)" "92^(@)" "91^(@)" "90^(@)`