The least stable hydride is

Options

A. `PH_(3)`
B. `AsH_(3)`
C. `SbH_(3)`
D. `BiH_(3)`

Answer

4

Explanation

The hydrides show regular graduation in their properties ,The thermal stability of the hybrides decreases (due to decrease fo `Delta_("diss")H^(Ɵ)(E-H)]` as we move from `NH_(3)` to `BiH_(3)`. Thus `NH_(3)` is most stable ,the stability of `PH_(3), AsH_(3)` and `SbH_(3)` decreases progrssively while `BiH_(3)` is the least stable.
Order of thermal stability:
`NH_(3) gt PH_(3) gt AsH_(3) gt SbH_(3) gt BiH_(3)`
`BiH_(3)` is so unstable that it has a half -life of only `20` minutes at ordinary temperatures.