Question

Basic character of hydrides of group 15 is due to the presence of lone pair on the central atom.

1. NH₃ is strongly basic while BiH₃ is weakly basic. Why?

2. Differentiate between allotropic forms of phosphorus.

Answer 1

1. Due to the presence of lone pair of electrons on nitrogen atom of NH₃. But in BiH₃,due to the large size of Bi the electron density decreases and hence is less basic.

2. The allotropic forms of P are White, Red and Black phosphorus. White phosphorus consists of tetrahedral P molecules. Red phosphorus is polymeric in structure consisting of chains of P tetrahedra linked together. Black phosphorus has a layer type structure and has α and β forms.