Which is the correct thermal stability order for H2E (E = O, S, Se, Te and Po)?
- H2Po < H2Te < H2Se < H2S < H2O
- H2Se < H2Te < H2Po < H2O < H2S
- H2S < H2O < H2Se < H2Te < H2Po
- H2O < H2S < H2Se < H2Te < H2Po
Answer
(1) H2Po < H2Te < H2Se < H2S < H2O
Solution
As per NCERT, down group 16 the size of E increases ⇒ the H–E bond becomes longer and weaker (bond dissociation enthalpy decreases).
⇒ Thermal stability of hydrides decreases from H2O to H2Po.
∴ H2Po < H2Te < H2Se < H2S < H2O
Answer: (1)