Which is the correct thermal stability order for $\mathrm{H}_{2} E$ ( $E=\mathrm{O}, \mathrm{S}, \ma

Question

Which is the correct thermal stability order for $\mathrm{H}_{2} E$ ( $E=\mathrm{O}, \mathrm{S}, \mathrm{Se}, \mathrm{Te}$ and Po ) ?\

Professor PC Thomas Classes · Answer

(d) : The thermal stability of hydrides decreases from $\mathrm{H}_{2} \mathrm{O}$ to $\mathrm{H}_{2} \mathrm{Po}$. This is because as the size of atom $E$ in $\mathrm{H}_{2} E$ increases, the bond $\mathrm{H}-E$ becomes weaker and thus, breaks on heating. Therefore, the correct order of thermal stability is $\mathrm{H}_{2} \mathrm{Po}<\mathrm{H}_{2} \mathrm{Te}<\mathrm{H}_{2} \mathrm{Se}<\mathrm{H}_{2} \mathrm{~S}<\mathrm{H}_{2} \mathrm{O}$.