NEET2026ChemistryChapterActual
In which of the following arrangements is the given sequence not strictly according to the property indicated against it?
Options
- AH₂O > H₂S > H₂Se > H₂Te : Decreasing bond angle
- BNH₃ < PH₃ < AsH₃ < SbH₃ : Increasing thermal stability
- CHClO < HClO₂ < HClO₃ < HClO₄ : Increasing acidic strength
- DHF < HCl < HBr < HI : Increasing reducing character
Correct answer
B. NH₃ < PH₃ < AsH₃ < SbH₃ : Increasing thermal stability
Step-by-step solution
The thermal stability of hydrides of Group 15 elements decreases down the group. This is because the size of the central atom increases down the group, which leads to an increase in the M-H bond length and a corresponding decrease in the bond dissociation enthalpy. Therefore, the correct order of thermal stability is NH₃ > PH₃ > AsH₃ > SbH₃ . The given sequence NH₃ For the other options: The bond angle of Group 16 hydrides decreases down the group due to decreasing electronegativity of the central atom ( H₂O > H₂S