Question

Which of the following are used as black pigment in black ink?
A.Carbon black
B.Germanium
C.Graphite
D.Coke

Answer 1

Hint: Pigments are intensely coloured material which are used to give colours to other substances. Pigments are usually completely or nearly soluble in water. Pigments are inorganic compounds.

Complete step by step answer:
Carbon black is an extensively used black pigment. Black colour of black ink is also imparted using carbon black.
Hence the correct option is A.
Carbon black is mainly produced by burning heavy petroleum products like coal tar, FCC tar and ethylene cracking tar in the atmosphere. It can also be produced in a small amount from vegetable oil. Carbon black consists of solid, opaque particles suspended in ink in order to provide colour. The molecules of pigment are linked together in crystalline structure that are $0.1$ to $2$ nm in size and occupy $5$ to $30$ percent of the total ink volume. The other properties of ink such as saturation, hue and lightness depend on the source and type of the pigment.

Additional information-
Carbon black consists of fine particles mainly made up of carbon. Properties of carbon black can be changed by controlling the combustion of oil and gases during their production. Another main use of carbon black is in tyres because it is good in rubber reinforcement. Carbon black produced from vegetable oil can be used for food colouring.

Note:
Graphite can be used as a black pigment in casting resins. Coke is also produced by heating coal and oil. But it is mainly used as fuel and as a reducing agent. Germanium is mainly used in semiconductors.