Question

A student tested the $pH$ of distilled water and found that the colour of $pH$ paper changed to green. He checked the $pH$ again after dissolving a pinch of common salt in water. The colour of the $pH$ paper this time was:

• A. green
• B. yellow
• C. red
• D. blue

Answer 1

Answer: (A)

green

(a) The $pH$ paper in neutral medium gives green colour.
Sodium chloride ($NaCl$) is a salt of strong base (NaOH) and strong acid ($HCl$). It dissolves in water to give a neutral solution which is just like distilled water. Therefore, the colour of pH paper remained green.