Question

The indigo plant is used in making the dye for________________
A) Textiles
B) Steelmaking
C) Coal refining
D) Oil refineries

Answer 1

Hint: The term Indigo means ‘the Indian’ or ‘from India’. Even though indigo plants are believed to be native to India, they are also present in the tropical zones of Africa and China. More than 5,000 years ago, our ancestors in India, East Asia, and Egypt, as well as the Mayas, started using the blue dye derived from the Indigofera Tinctoria plant to dye their clothes in blue and purple colors.

Complete step by step answer:
Indigo dye is a blue coloured organic compound. It was a naturally made dye before synthetic coloring was added and it is extracted from the leaves of plants of the Indigofera genus, especially from a plant called Indigofera tinctoria. These plants are commonly found and used across the world, mostly in the Asian subcontinent. It is grown as an important crop, associated with the production of indigo dye, and is important to the economy due to the previous rarity of natural blue dye. The dye has a chemical formula of C12H10N2O2, generally known as 〖2,2〗^'-Bis(2,3-dihydro-3-oxoindolyliden) or Indigotin.
Commercial-scale indigo species in Asia include ‘true indigo’ (Indigofera tinctoria, also known as Sumatrana). This plant is commonly used as an alternative color agent in colder subtropical locations of Asia such as Japan and Taiwan. These plants produce indigo dye when exposed to oxygen. However, the dye will be in low concentrations, making it difficult to extract. The colour will be tainted by other dyeing substances present in these plants which will change the dye colour to a typical greenish tinge. India was the major supplier of indigo in the European market during the Greco-Roman era. The major use of this dye is in the textile industry especially as a dye for cotton yarn, which is largely used in the production of denim (blue jeans). Smaller quantities are also used in the dyeing of wool and silk. Indigo carmine, which is known as indigo, is also used as an indigo derivative colorant.

So, the correct answer is Option :

Note: Denim was created from a fabric known as "serge de Nimes." It was created to be a long-lasting and robust fabric in Italy which later identified as Levi jeans. The chemical structure of indigo dye was identified by Adolf Bayer in 1897 and was synthesized 14 years later. Because of its high value as a trading commodity, indigo was often referred to as blue gold in the market. Workers in Bengal revolted because of the unfair treatment by the East India Company traders/planters in what became known as the Indigo revolt in 1859.