Chapter 3, Problem 27P

The bond lengths of the $\text{X}-\text{H}$ bonds in ${\text{NH}}_{\text{3}},{\text{PH}}_{\text{3}}$ , and ${\text{SbH}}_{\text{3}}$ are 1.02, 1.42, and 1.71 Å, respectively. Estimate the length of the $\text{As}-\text{H}$ bond in ${\text{AsH}}_{\text{3}}$ , the gaseous compound that decomposes on a heated glass surface in Marsh’s test for arsenic. Which of these four hydrides has the weakest $\text{X}-\text{H}$ bond?