Question

Is the dye in black ink a single colour?

NCERT Class IX
Sciences - Main Course Book

Chapter 2. Is Matter Around Us Pure

Answer 1

the ink that we use has water as the solvent and the dye is soluble in  it.as the water rises on the filter paper it takes along with it the dye  particles. usually,a dye is a mixture of 2 or more colours.  

Answer 2

The ink that we use has water as the solvent and the dye is soluble in it. As the water rises on the filter paper it takes along with it the dye particles. Usually, a dye is a mixture of two or more colours. The coloured component that is more soluble in water, rises faster and in this way the colours get separated.

This process of separation of components of a mixture is known as chromatography. Kroma in Greek means colour. This technique was first used for separation of colours, so this name was given.

Chromatography is the technique used for separation of those solutes that dissolve in the same solvent.

With the advancement in technology, newer techniques of chromatography have been developed. You will study about chromatography in higher classes.