Question

A student dipped a pH paper first in distilled water and then aqueous NaCl solution. In both the cases, the colour of the pH value remained green. What does it indicate ?

Answer 1

• pH is the measure of the concentration of ${\mathrm{H}}^{+}$ions and it expresses the acidic or basic nature of the solution.
• The pH scale imparts different colors depending on the pH value of the solution.

pH	acidic/ basic/ neutral	color
>3	acidic	red
4-6	acidic	orange
7	neutral	green
8-11	basic	blue
11-13	basic	purple
14	basic	violet

The green colour of pH paper indicates neutral pH. This implies that water and NaCl solution are neutral in nature.

Hence, NaCl solution and water are neutral in nature.