4.Give examples, which indicate that nylon fibres are very strong
5. Name the plastic whose sheets are used for packing liquids.
6. How is artificial silk made?
7. Why nylon is used for making parachutes?
8. Can bacteria break down plastics?
9. Write any tree important properties and uses of nylon.
10. Give the characteristic properties and important uses of the following (i). Polythene (ii). Polystyrene (iii). Teflon
Answers
Answer:
ans 4 The following examples indicate that nylon fibres are very strong :
Nylon is used in making parachutes.
It is used in making ropes for rock climbing.
It is used in making sport accessories like rackets.
It is used in making ropes of boats.
It is used for making fishing nets,seat belts,etc.
ans 5 Name the plastics whose sheets are used for packing liquids. For packaging of liquids plastic used is polyethylene terephthalate which is a polymer of ethylene terephthalate.
ans 6 Artificial silk, or rayon, is made from cellulose, obtained from cotton or wood pulp. The cellulose is dissolved in a substance called alkaline carbon disulphide to make a thick liquid. This is squirted through tiny holes into a bath of acid. It reforms as fibres, which can be spun into yarn.
ans 7 Nylon - Nylon replaced silk during the WW2 when supply of silk diminished. Nylon has since become a popular choice, as it has excellent wind resistance, good elasticity, mildew resistance, and is comparatively cheaper. The material is also lightweight and dries quickly. It is resistant to abrasion and chemicals.
ans 8 Scientists have discovered bacteria that are able to biodegrade plastics from polymers back into ... ... After scooping up some sludge from outside a bottle recycling facility in Osaka, they discovered bacteria which had developed the ability to decompose, or “eat,” plastic
ans 9 Nylon fabric became important as a synthetic substitute for silk in the manufacture of parachutes when silk became scarce during WWII. Nylon is still used today to make parachute canopies due to its elasticity, strength, resistance to mildew, availability and price.
ans 10 1) It is water resistant. 2) It is strong but flexible and can be rolled into sheets and moulded into different shapes. ... Polythene pipes are used to transport liquids such as oil and water. Polythene containers are used to store liquids