Question

The color of universal indicator solution is __________
(a)- Red
(b)- Blue
(c)- Green
(d)- Greenish-yellow

Answer 1

Hint: Universal indicator is a substance mostly used by the chemist in testing the presence of acid or base in the compound. The red color is produced when the solution is acidic and the Purple color is produced if the solution is basic.


Complete step by step answer:
A pH indicator that is made from several compounds that shows several smooth color changes over a wide range of pH values to indicate the acidity or alkalinity of the solution is known as a universal indicator.
The main compositions of the universal indicator are water, 1-Propanol, phenolphthalein sodium salt, methyl red, sodium hydroxide, thymol blue monosodium salt and bromothymol blue monosodium salt.
 The color of the neutral universal indicator is greenish-yellow, i.e., the pH is 7 of the solution.
The universal indicator will give orange or yellow color if the solution is a weak acid. The pH of the solution will range from 3-6.
The universal indicator will give red color if the solution is a strong acid. The pH of the solution will range from 0-3.
The universal indicator will give blue color if the solution is a weak base. The pH of the solution will range from 8-11.
The universal indicator will give violet or purple color if the solution is a strong base. The pH of the solution will range from 11-14.

So, the correct answer is an option (d)- Greenish yellow.



Note: The universal indicator is available in two forms, i.e., paper form, and solution form. The paper form is usually known as litmus paper, it turns blue in basic and turns red in acidic medium. In solution form, the loss or gain of the proton is the basis for the change in color of the solution.