Which statement about acids is true?

• A. Acids produce OH- in water.
• B. Acids donate H+ ions in aqueous solution.
• C. Acids have a pH greater than 7.
• D. Acids do not react with litmus.

Answer: (B)

Acids raise the concentration of hydrogen ions when they dissolve in water. The hydrogen ions don’t stay free for long; they quickly bond with water molecules to form hydronium ions (H3O+), which makes the solution acidic (pH less than 7). This behavior is the defining trait of acids in aqueous solutions. That’s why acids turn blue litmus red and react with litmus—indicating an acidic environment. The other statements don’t fit because acids do not produce hydroxide ions (that’s a property of bases), they do not have a pH greater than 7 (that would be basic), and they do react with litmus.