Question

Which statement is incorrect?
A. pH scale was presented by S.P.L Sorensen
B. pH scale ranges between 0 and 14
C. pH scale is applicable to only non-aqueous solutions.
D. pH scale is applicable to only aqueous solutions

Answer 1

Hint: When measuring pH, the negative logarithm of the concentration of hydrogen is taken. It can be only done if the hydrogen ions are able to move about freely in the solution, it only happens in a specific type of solution.

Complete step by step answer:
In chemistry, pH is referred to as the potential of hydrogen. pH is a standard scale that is used to measure how much acidic or basic a solution is. pH was invented by S.P.L Sorensen and the scale ranges from the value of 0 to 14. As we progress right in the scale, the acidic character reduces and the basic character increases. Solutions which have pH close less than 7 are said to be acidic, whereas those with pH more than 7 are basic.
At pH=7 the solution is said to be neutral, as it has equal amounts of ${{H}^{+}}$ and $O{{H}^{-}}$ ions.
Here is the pH scale:

So, on dipping a pH paper in a solution, we get a colour and by identifying the colour, we can get the respective pH values.
Mathematically pH is represented by: $pH=-\log [{{H}^{+}}]$, so pH depends on the concentration of hydrogen ions present in the solution. However, for that to happen the solution must be aqueous. Only in aqueous solutions the ions get dissociated, and dissociation does not take place in non-aqueous solutions.

So, pH scale does not apply only to non-aqueous solutions. Hence, it is the incorrect statement and we obtain our answer as option C.

Note: As $pH=-\log [{{H}^{+}}]$, hence it is a decreasing function. A solution that has more ${{H}^{+}}$ in it will have more pH. Moreover, the pH of pure water at ${{25}^{0}}C$is equal to 7. Temperature also plays a role in determining the pH.