Which statement about acids is correct?
They have a pH value greater than 7.
They release hydroxide ions (OH−\text{OH}^-OH−) in aqueous solution.
They react with metal carbonates to produce carbon dioxide gas.
They turn red litmus paper blue.
55 exam-style questions on OCR GCSE Chemistry Types of chemical reactions. Each one has a worked solution and a mark scheme showing where the marks go.