Question

Why is \[Bi{H_3}\] the stronger reducing agent amongst all the hydrides of group \[15\] elements?

Answer 1

Hint: The hydrides are the reducing agents that are formed from the different atoms like oxygen and hydrogen. In these compounds’ hydrogen will exist as a hydride ion which is an anion. The stability of hydrides is inversely proportional to the reducing character of hydrides.

Complete answer:
Periodic table consists of elements arranged in the vertical columns and horizontal rows. The vertical columns were called groups and the horizontal rows were called periods.
The elements in the group \[15\] are called nitrogen family or pnicogens.
The elements in the group \[15\] are nitrogen, phosphorous, arsenic, antimony and bismuth.
These all-elements form hydrides when combined with hydrogen atoms. In hydrides the hydrogen atom exists as an anion, it is the special property of hydrides. As hydrogen exists as cation in most of the cases except in the case of hydrides.
The stability of these hydrides is inversely proportional to the reducing character.
The stability of these hydride decreases while moving down the group. The nitrogen hydride is more stable and bismuth hydride is least stable.
Due to the least stability of bismuth hydride, it is the strongest reducing agent among all the hydrides of group \[15\] elements.
Thus, \[Bi{H_3}\] the stronger reducing agent amongst all the hydrides of group \[15\] elements.
Thus option A is the correct answer.

Note:
The elements that form hydrides are generally involved in covalent bonding as the electronegativity of hydrogen is less and the metal atom involved other than hydrogen also has low electronegativity. The elements other than hydrogen have more electropositivity like sodium.