2019 The p-Block Elements (Group 15 to 18)Group 16 Elements – Hydrides Easy Question 2 of 2 in Group 16 Elements – Hydrides

Which is the correct thermal stability order for $H_2E$ (E = O, S, Se, Te and Po)?

A $H_2S<H_2O<H_2Se<H_2Te<H_2Po$
B $H_2O<H_2S<H_2Se<H_2Te<H_2Po$
C $H_2Po<H_2Te<H_2Se<H_2S<H_2O$
D $H_2Se<H_2Te<H_2Po<H_2O<H_2S$

The answer is C.

Solution

On going down the group, the H–E bond dissociation enthalpy decreases, so the thermal stability of $H_2E$ decreases. Order of stability: $H_2Po<H_2Te<H_2Se<H_2S<H_2O$

Concept thermal stability of group 16 hydrides

Group 16 Elements – Hydrides in past papers

2 questions from this chapter have appeared across 2 exam years.