Question

MENTION HOW CHANGE IN COLOUR IS IDENTIFIED​

Answer 1

Explanation:

Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. ... Pearlescence is a related effect where some or all of the reflected light is white, where iridescent effects produce only other colours.

Answer 2

Explanation:

When universal indicator is added to a solution, the color change can indicate the approximate pH of the solution. Acids cause universal indicator solution to change from green toward red. Bases cause universal indicator to change from green toward purple.