Question

Arrange the given compounds in the decreasing order of their pH.
$NaCl$, $NaOH$, $C{H}_{3}COOH$, $H_{2}S{O}_4$

• A. $NaCl$ > $NaOH$ > $C{H}_{3}COOH$ > $H_{2}S{O}_4$
• B. $H_{2}S{O}_4$ > $C{H}_{3}COOH$ > $NaCl$ > $NaOH$
• C. $NaOH$ > $C{H}_{3}COOH$ > $H_{2}S{O}_4$ > $NaCl$
• D. $NaOH$ > $NaCl$ > $C{H}_{3}COOH$ > $H_{2}S{O}_4$

Answer 1

The correct option is D $NaOH$ > $NaCl$ > $C{H}_{3}COOH$ > $H_{2}S{O}_4$

The basic and acidic nature of a solution is determined by measuring the hydrogen ion concentration present in it. This concentration can be measured by a pH scale. The table given below shows the approximate pH range of the acidic, basic and neutral solutions. $$\begin{array}{cc}\text{Type of solution}& \text{Approx. pH range}\\ \text{Acidic}& \text{0 - 7}\\ \text{Neutral}& \text{7}\\ \text{Basic}& \text{7 - 14}\end{array}$$

• $H_{2}S{O}_4$ and $C{H}_{3}COOH$ will have pH in the range of 0 to 7 while $H_{2}S{O}_4$ being strong acid will have less pH than $C{H}_{3}COOH$.
• Since $NaCl$ is a neutral salt, it will have pH equivalent to 7.
• $NaOH$ being a strong base will have pH in the range of 7 - 14.

Hence, arranging above compounds based on pH in descending order: $NaOH$ > $NaCl$ > $C{H}_{3}COOH$ > $H_{2}S{O}_4$