Answer: The correct answer is Acids measure below 7.
pH ( Potential of hydrogen) is used to measure the basicity ( alkalinity) or acidity of water soluble substances.
The value on pH scales lies from 0 to 14 where 7 indicates a neutral pH that corresponding to neutral solutions like water.
Any value below 7 indicates that the solution is acidic ( like Hydrochloric acid) and above 7 indicates that the solution is alkaline ( base like sodium hydroxide).
Thus, acids measure below 7 is the right answer.
