Which is the substitute of glass Polyester, Nylon, Rayon, polythene
Answers
Answer:
Fibres And Plastics - Meritnation
Answer: (a) Perspex This is used as a substitute for glass because it is transparent and unbreakable. ... Examples of synthetic fibres: nylon, rayon and polyester ...
Page No 45:
Question 1:
Give two examples each of natural and synthetic fibres.
ANSWER:
Examples of natural fibres:
1) Cotton
2) Silk
Examples of synthetic fibres:
1) Nylon
2) Polyester
Page No 45:
Question 2:
What is a polymer?
ANSWER:
The word ‘polymer’ comes from two Greek words ‘poly’ meaning many and ‘mer’ meaning part or unit. When smaller units of a chemical substance are combined to form a large single unit, it is called a polymer. Examples are cellulose, polythene etc.
Page No 45:
Question 3:
Why is rayon called a regenerated fibre?
ANSWER:
Rayon is called a regenerated fibre because its preparation involves the chemical breakdown of cellulose using an alkaline solution. This is followed by the regeneration of solidified synthetic fibres by passing them through spinnerets.
Page No 45:
Question 4:
List two disadvantages of synthetic fibres.
ANSWER:
Two disadvantages of synthetic fibres are:
1) Synthetic fibres can’t absorb moisture, which makes them unsuitable during summer. They stick to the body and cause skin irritation when the body sweats during summers.
2) They are dangerous to be worn near fire or heat as they can catch fire easily.
Page No 45:
Question 5:
What is a plastic? All plastics have one common property−what is it?
ANSWER:
Plastic is a synthetic material made from a wide range of organic polymers such as polyethylene, PVC, nylon etc., that can be moulded into shape while soft, and then set into a rigid or slightly elastic form.
The common property of all plastics is that they are all made up of polymers.
Page No 45:
Question 6:
Why are plastic bottles commonly used to store chemicals in a chemistry laboratory?
ANSWER:
Plastic bottles are commonly used to store chemicals in a chemical laboratory because plastics are non-reactive. They are inert to
Uses:
It is used for the packaging of delicate materials like electronic items. It is used to make thermocol. It is also used to insulate the hollow walls of the refrigerator.
(c) The properties and uses of teflon are as follows:
Properties:
1) It is slippery and is not affected by heat.
2) It does not react chemically with other substances.
Uses:
It is used as a non-stick coating on pans and other cooking utensils. It is used for making gaskets, pump packings, valves, seals etc.
(d) The properties and uses of bakelite are as follows:
Properties:
1) It is a good electrical insulator.
2) It is harder than other plastics.
Uses:
It is used to make electrical goods, combs, fountain pens, buttons, plugs and switches.
Page No 46:
Question 1:
Do you think rayon when burnt will stick to the body like other synthetic fibres?
ANSWER:
Synthetic fibres catch fire very easily. They melt on heating and stick to the body of the person wearing them. However, rayon is regenerated from cellulose and it doesn't melt on burning, rather it flares up like paper and smells like it.