Question

Which of the following is acidic in nature?
(A) Apple juice
(B) Soap solution
(C) Slaked lime
(D) None of the above

Answer 1

Among the given options two are alkaline in nature and one is acidic in nature. The substance has a sour taste. Because of the low pH of the substance, consuming this in higher concentrations can lead to gastrointestinal problems and dental erosion.

Complete step by step solution:
-The termbase and acid have been defined in several ways in chemistry. Normally, we can say that an acid is any hydrogen-containing substance which is capable of donating a hydrogen ion or proton to another substance.
-The solutions can be classified as basic or acidic depending on their hydrogen ion concentration relative to pure water. If the value of pH is below seven, then the solution is acidic and if the pH is greater than seven then the solution is said to be basic. For a neutral solution, the value of pH would be seven.
-Normally bases taste bitter due to the presence of hydroxyl ions and acids usually taste sour due to the presence of hydrogen ions. But depending on the other parts of the molecule they can have different tastes too.
-As we are aware, soap is made by the saponification reaction between a strong base and a weak fatty acid. The product formed that is the soap is a mildly weak base and it has a pH above seven. Thus, a soap solution is alkaline in nature and option (B) can be excluded.
-Slaked lime or calcium hydroxide ($Ca{{(OH)}_{2}}$) contains hydroxyl ions and thus slaked lime is also an alkaline substance. Hence, option (C) also can be excluded.
-We all know that; apple juice is a type of fruit juice made by softening and pressing the apple pieces into liquid. It has an acidic nature which is due to the presence of many acids. The major acid which is present in apple juice is malic acid.
-Apple juice also contains chlorogenic acid and quinic acid. As a result, the pH of apple juice occurs in a range of 3.35 to 4 and thus apple juice is acidic.

Thus, the answer is option (A) apple juice.

Note: Bear in mind that the pH level of apple juice is affected by the processing method and the taste of apple juice is also affected by acidity. An extremely acidic juice would be sharp in taste whereas a lower acidic juice will lack freshness in taste. Also, remember that malic acid is a dicarboxylic acid and a diprotic acid.