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(a) Name the halogen hydracid with highe...

(a) Name the halogen hydracid with highest bond energy.
(b) When HI solution is kept exposed to air, it turns brown after a few days. Why ?

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(a) The hydracid (HF) having the smallest halogen (i.e., F) has the hightest bond energy.
(b) Because of the largest size of halogen, the H-I bond is the weakest. When exposed to air, it decomposes to liberate `I_(2)` which gives brown colour to the solution.
`4HI + underset(("Air"))(O_(2)) rarr 2 H_(2)O + underset("Brown")(2I_(2))`
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