Which feature is common to the chemical formulas of all acids?

• A. They all end with OH, indicating hydroxide ions.
• B. They all have a carbon atom as the central atom.
• C. They all begin with H, indicating the presence of hydrogen ions.
• D. They all contain a metal as the first element.

Answer: (C)

Verified step by step guidance

1. Understand that acids are substances that release hydrogen ions (H\textsuperscript{+}) when dissolved in water.
2. Recognize that the chemical formulas of acids typically start with one or more hydrogen atoms, which is why they begin with 'H'.
3. Note that not all acids contain hydroxide ions (OH\textsuperscript{-}); hydroxide ions are characteristic of bases, not acids.
4. Acknowledge that many acids do not have carbon atoms as their central atom; only organic acids do, but inorganic acids do not necessarily contain carbon.
5. Realize that acids do not necessarily contain metals; many acids are composed of hydrogen and nonmetals.