Which of the following has lest covalent `P-H` bond ? .

Options

A. `PH_(4)^(+)`
B. `P_(2)H_(5)^(+)`
C. `P_(2)H_(6)^(2+)`
D. `PH_(3)`

Answer

3

Explanation

the covalent charter of `P-H` bond depends on the formal charge distributed on each `P-H` bond
In `PH_(4)^(+)` it is `+1//4=+0.25,` in `P_(2)H_(5)^(+)` it is `+1//5=+0.2` and in `P_(2)H_(6)^(2+)` it is `+2//6=+0.33`.
The higher the formal charge the lesser the covalent character due to more polarisation .Thus the least covalent `P-H` bond is present in `P_(2)H_(6)^(2+)`.