Paheli went to the market to buy sarees for her mother. She took out a thread from the edges of the two sarees shown by the shopkeeper and burnt them. One thread burnt with a smell of burning hair and the other burnt with the smell of burning paper. Which thread is from a pure cotton saree and which one from a pure silk saree? Give a reason for your answer.
In the case of the first saree, the thread burnt with a smell of burning hair is from pure silk. Silk and hair are protein fibres. So, on burning these threads, a smell of burning hair comes out. In the case of the second saree, the thread burnt with the smell of burning paper is from a cotton saree. Since cotton and paper both are carbohydrates and on burning they give a similar smell.