Consider the following statements regarding the hydrides of Group 17 elements: (I) The thermal stability of the hydrides follows the order HF > HCl > HBr > HI . (II) The reducing power of the hydrides follows the order HF (III) The boiling points of the hydrides follow the order HCl (IV) The acidic strength of the hydrides follows the order HI > HBr > HCl > HF . How many of the above statements are correct?

Step-by-step solution

Statement (I) is correct: Thermal stability decreases down the group as the H-X bond dissociation enthalpy decreases from HF to HI . Statement (II) is correct: Reducing power increases down the group because the decreasing bond enthalpy makes it easier to release hydrogen. Statement (III) is correct: HF has an anomalously high boiling point due to strong intermolecular hydrogen bonding. For the other hydrogen halides, the boiling point increases with molecular mass due to increasing magnitude of van der Waals force