Question

Four students a, b, c, and d measured pH values of water, lemon juice, and sodium bicarbonate solution. What is the correct decreasing order of the pH value?
(A) water > lemon juice > sodium bicarbonate
(B) lemon juice > water > sodium bicarbonate
(C) sodium bicarbonate > water > lemon juice
(D) water > sodium bicarbonate > lemon juice

Answer 1

Hint: This question is based on the concept of pH value regarding the acids, and bases. We have three compounds i.e. water, lemon juice, and sodium carbonate. Identify the acid, base, and neutral molecule among these, and the decreasing order could be known.

Complete step by step answer:
> First, let us know about the concept of pH scale. It is a kind of measuring tool used for determining the acidic, basic, and neutral compound.
>In the pH scale, litmus paper acts as an indicator.
> The pH scale ranges from the value of 0-14, basically pH is the concentration of hydrogen ions.
> We can say that the solution having the pH value ranging between 0 to 7 are acidic, and 7 to 14 are basic, and the value of pH equal to 7 are neutral solutions.
- Now, if we look at the options there are three compounds, i.e. sodium carbonate, lemon juice, and water.
- The first is sodium carbonate that is a strong base, so it has the pH value greater than 7.
- Second is lemon juice that is acidic in nature, thus the pH value is below 7.
- Third is water that is a neutral compound with the pH value 7.
Thus, we can say that the order of the value of pH followed is
Sodium carbonate > water > lemon juice.
Hence, the correct option is (C).

Note: Don’t get confused between the range variation on the pH scale. Just remember that it is divided into three parts on the basis of nature of molecules, or compounds, as mentioned. So, the knowledge of pH scale is helpful for the students to measure the range for different compounds.