Question

The correct order of thermal stability of hydrogen halides (H – X) is

• A. HI >HBr>HCl> HF
• B. HF >HCl>HBr> HI
• C. HCl> HF >HBr> HI
• D. HI >HCl> HF >HBr

Answer 1

The correct option is B

HF >HCl>HBr> HI

Thermal stability is directly proportional to bond dissociation energy and bond dissociation energy is inversely proportional to bond length. The decreasing order of bond dissociation energy is HF>HCl>HBr> HI and hence order of thermal stability is HF >HCl>HBr> HI.