Which of the following compounds contains the weakest bonds to hydrogen?

• A. HBr
• B. HF
• C. HCl
• D. HI

Answer: (D)

Verified step by step guidance

1. Step 1: Understand that the strength of the bond between hydrogen and a halogen (X) in HX depends largely on the bond dissociation energy, which is influenced by the size and electronegativity of the halogen atom.
2. Step 2: Recall that bond strength generally decreases as the size of the halogen atom increases because larger atoms form longer and weaker bonds with hydrogen.
3. Step 3: Recognize the order of halogen atomic size: F < Cl < Br < I, meaning fluorine is the smallest and iodine is the largest.
4. Step 4: Since bond strength decreases with increasing atomic size, the H–I bond will be weaker than H–Br, H–Cl, and H–F bonds.
5. Step 5: Therefore, the compound with the weakest bond to hydrogen is HI, because iodine forms the longest and weakest bond with hydrogen among the given options.