Question

Arrange halogen acids in the decreasing order of reducing power.

Answer 1

Reducing power increases from HF to HI. HI is the strongest reducing agent; HF is the weakest. This is because bond dissociation energy decreases from HF to HI, making HI easier to lose electrons (reduce) than others. Hence, the decreasing order is HI > HBr > HCl > HF. This is the standard order of reducing power of halogen acids.