Question

The least stable hydride of $15^{th}$ group elements is

• A. $N{H}_3$
• B. $P{H}_3$
• C. $As{H}_3$
• D. $Sb{H}_3$
• E. $Bi{H}_3$

Answer 1

Answer: (E)

Thermal stability of hydrides of N family decreases gradually from $N{H}_3$ to $Bi{H}_3$ due to increase in $MH$ bond strength down the group on account of increase in size of central atom.
$N{H}_3>P{H}_3>As{H}_3>Sb{H}_3>Bi{H}_3$
Decomposit $1300{}^{\circ }C440{}^{\circ }C280{}^{\circ }C150{}^{\circ }C$
Room ion temp. : temp.