Explanation:
A pH helps us to determine whether a solution is basic or acidic in nature.
If pH is less than 7 then the substance or solution is acidic in nature and if pH is more than 7 then the substance or solution is basic in nature.
Also, acids are sour in taste whereas bases are bitter.
Thus, we can conclude that the bottle whose label have fallen off contains an acid and the pH of this liquid is MOST likely less than 7.