Which of the following compounds forms a strong acid and also contains a halogen?

• A. Li2O
• B. H2S
• C. HBr
• D. LiBr

Answer: (C)

Verified step by step guidance

1. Identify what defines a strong acid: a compound that completely dissociates in water to release H\textsuperscript{+} ions.
2. Review each compound to determine if it contains a halogen (elements from Group 17: F, Cl, Br, I, At).
3. Check if the compound is an acid and if it is strong. For example, HBr is a hydrogen halide known to be a strong acid.
4. Analyze Li2O: it contains lithium and oxygen, no halogen, and is a basic oxide, not an acid.
5. Analyze H2S: it contains hydrogen and sulfur, no halogen, and is a weak acid; LiBr contains lithium and bromine (a halogen) but is a salt, not an acid.