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