Paheli went to the market to buy sarees for her mother. She took out a thread from the edge of the two sarees shown by the shopkeeper and burnt them

cbse
cbse-class-7-science
fibre-to-fabric

#1

Paheli went to the market to buy sarees for her mother. She took out a thread from the edge 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 reason for your answer.

Answer:
The thread which burns with a smell of burning hair is from pure silk. This is because silk and hair are protein fibres, therefore, they produce similar smell on burning. Whereas cotton and paper both are carbohydrates, thus the thread which burns with the smell of burning paper is from cotton saree.