Which of the following has the highest boiling point?

Options

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

Answer

1

Explanation

The boiling points increases regularly as we move from `PH_(3)` To `BiH_(3)`. However , the boiling point of `NH_(3)` is higher than those of `PH_(3)` and `AsH_(3)` but lower than those of `SbH_(3)` and `BiH_(3)`
On account of very high electronegativity of `N` ,ammonia undergoes intermolecular `H`- bonding while other hydrides do not form intermolecular `H-`bonds on account of low electronegativities of central atoms.
As we move from `PH_(3)` and `BiH_(3)`, the miolecular mass increases causing a corresponding increase in the strength of the vander Waals forces of attraction. Consequently the boiling point increases regularly from `PH_(3)` to `BiH_(3)`
The incresases in the boimg oint of `SbH_(3)` and `BiH_(3)` because of increasing in bpt of `NH_(3)` becasue of `H`-bonding.