Assign a reason for each of the following statements : (i) Ammonia is a stronger base than phosphine. (ii) Sulphur in vapour state exhibits a paramagnetic behaviour.

Assign a reason for each of the following statements : (i) Ammonia is

1.	Assign a reason for each of the following statements : (i) Ammonia is a stronger base than phosphine. (ii) Sulphur in vapour state exhibits a paramagnetic behaviour.
Answer» Solution :(i) Due to the PRESENCE of lone pair of electrons on the CENTRAL atom both `NH_(3)` and `PH_(3)` are Lewis Bases. When `NH_(3)` or `PH_(3)` accepts a proton, an additional N-H or P-H bond is formed. `H_(3)N : + H^(+) rarrNH_(4)^(+), H_(3)P : + H^(+) rarrPH_(4)^(+)` Due to smaller size of N than P, N-H bondthus formed is much stronger than P-H bond. As a result `NH_(3)` has more tendency than `PH_(3)` to accept a proton. Therefore, `NH_(3)` is stronger base than `PH_(3)`. (ii) In vapour state sulphur partly exists as `S_(2)` molecule which has two UNPAIRED electrons is the artibonding `pi**` ORBITALS like `O_(2)` and hence, exhibits paramagnetism.