Identify the correct order of thermal stability for the hydrides ${\text{H}}_2\text{O}$, ${\text{H}}_2\text{S}$, ${\text{H}}_2\text{Se}$, ${\text{H}}_2\text{Te}$, and ${\text{H}}_2\text{Po}$.

Solution

1. Thermal stability of group 16 hydrides depends on the $\text{E-H}$ bond dissociation energy.
2. As the atomic size of the central atom increases down the group, the bond length increases.
3. Increased bond length leads to a decrease in bond dissociation enthalpy.
4. Hence the answer is (A).