A student tests a concentrated solution of methanoic acid. The pH is below 7. The student concludes that methanoic acid must be a strong acid.
Which statement explains why the student's conclusion is incorrect?
Weak acids also release hydrogen ions, because a small proportion of their molecules ionise
A concentrated acid cannot be strong, because strong acids are only found as dilute solutions
Weak acids also lower the pH, because their un-ionised molecules make the solution acidic
Weak acids also release hydrogen ions, because a concentrated solution makes all their molecules ionise
97 exam-style questions on AQA GCSE Chemistry 7.2 Reactions of alkenes and alcohols, covering 7.2.1 Structure and formulae of alkenes, 7.2.2 Reactions of alkenes, 7.2.3 Alcohols, 7.2.4a Carboxylic acids, and 7.2.4b Carboxylic acids as weak acids. Each one has a worked solution and a mark scheme showing where the marks go.