Q) What is a polymer ? Name the natural polymer of which cotton is made.
A: A polymer is a very big molecule formed by the combination of a large number of a small molecules. Cotton is made up of cellulose.
Q) What is polymerisation ?
A: The chemical process of making polymer is called polymerisation.
Q) Define the term Synthetic .
A: The term synthetic means made by humans in an industrial process.
Q) Name the units of which cellulose polymer is made?
A: Cellulose polymer is made up of a large number of small glucose molecules joined one after the other.
Q) Name the man made fibre prepared from natural materials.
A: Rayon is a man-made fibre made from a natural material called cellulose, which is obtained from wood pulp.
Q) Name the man-made fibre which is regarded as artificial silk.
A: Rayon is the man-made fiber which is often regarded as artificial silk.
Q) How many major types of synthetic fibers are there and what are they ?
Q) Name the major types of synthetic fibers .
A) There are four major types of synthetic fibers. They are Rayon, Nylon, Polyester, and Acrylic.
Q) Which synthetic fibers are prepared from petrochemicals?
A: Nylon, polyster and acrylic are made from petrochemicals.
Q) What is wood pulp?
A: Wood pulp is a soft, wet mass of fibers obtained from wood.
Q) Why rayon is semi-synthetic fibre ?
A: Rayon is obtained from a natural material called wood pulp but through chemical process in factories. There fore rayon is a semi-synthetic fibre.
Q) Write the uses of rayon.
A: Rayons can be used :
- to make sarees blouses and dresses
- to make furnishings such as bed-sheets, curtains and blankets.
- to make carpets
- to make bandage and surgical dressing
- to make tyre cord.
Q) Name the first fully synthetic fibre.
A: Nylon is the first fully synthetic fibre.
Q) What is Nylon ? State the important properties of nylon.
A: Nylon is a synthetic fibre. Some of the important properties are strength, fairly elasticity, lightweight, lustrous.
Q) Give the important uses of Nylon.
A: Nylon can be used :
- in making textile fabrics like sarees and other garments.
- in making curtains, sleeping bags and tents.
- as a thread where strength is required because it is stronger then a steel wire of similar thickness.
- as a plastic for making machine parts
Q) Why it is called Nylon?
A: It was developed in New York and London. First letter of New, First letter of York, First three letters of London combinedly formed NYLON.
Q) What is polyster ? Name a popular polyster.
A: Polyester is a synthetic fibre. Terylene is a popular polyster.
Q) Which synthetic fibre contains the organic group similar to those which give fruits their sweet smell ?
A: Polyester contains repeating units of easter which gives fruit their sweet smell.
Q) Arrange the following fibres in the order of increasing strength (keeping the fibre of least strength first) : Nylon, Cotton, Wool, Polyester, Silk.
A: In the order of increasing strength the fibres are : Wool, Cotton, Silk, Nylon, Polyester.
Q) What is PET ? State the uses of PET.
A: PET is a very familier form of Polyester. PET is used for making bottles, jars and utensils.
Q) What is acrylic ? State one important property of acrylic.
A: Acrylic is a synthetic fibre made from a chemical called ‘acrylonitrile’ by the process of polymerisation. One important property of Acrylic is it’s light weight.
Q) Write the uses of acrylic fibres.
A: Due to it’s wool-like feel, and less expensiveness, it is used for making sweaters, shawls, blankets, jackets, sportswear, socks etc.
Q) Why should we not wear clothes made of synthetic fibres (like nylon and polyester) while working in the kitchen?
A: Synthetic fibres melt on heating. If it catch fire accidently then it will melt and stick to the body of the person causing severe burns. So we should not wear this type of cloth while working in the kitchen.
Q) What type of shirts should we buy for summer : cotton shirts or shirts made from synthetic materials like polyester ? Give reason for your answer.
A: Shirts made of synthetic fibres donot have sufficient pores for the sweat to come out, evaporate and cool our body. So we should use cotton shirts which have sufficient pores for the sweet to come out, evaporate and cool our body during summer.
Q) Explain how, manufacturing of synthetic fibres is actually helping in the conservation of forests.
A: Fully synthetic fibres like nylon, polyester, acrylic etc are manufactured from petrochemicals obtained form crude oil ‘petroleum’, so no trees have to be cut down. This helps in the conservation of forests.
Q) What are plastics ? Name any five commonly articles made of plastics.
A: Plastics are synthetic materials which can be moulded into desired shapes when they are soft and then hardened to produce a durable article. Five commonly articles made of plastic are water bottles, buckets, mugs, combs and toys.
Q) What are the various types of plastics ? Give two examples of each type of plastics.
A: There are two types of plastics 1. thermoplastics and 2. thermosetting plastics. Two examples of thermoplastics are 1. polythene and 2. polyvinyl chloride also know as PVC. Two examples of thermosetting plastics are bakelite and melamine.
Q) Why are thermoplastics not used for making frying pan handles ?
A: Thermoplastics get soft or melt when heated so it is not used for making frying pan handle.
Q) Explain why, frying pan handles are made of thermosetting plastics ?
A: Thermosetting plastics when heated for the first time, they become soft or melt and can be moulded to make desired shaped article. On cooling it becomes very hard and rigid. If heated again it does not become soft at all. So it is used to make frying pan handle.
Q) Why are electric switches, plugs and sockets made of thermosetting plastics ?
A: Thermosetting plastics when heated for the first time, they become soft or melt and can be moulded to make desired shaped article. On cooling it becomes very hard and rigid. If heated again it does not become soft at all. So electric switches, plugs and sockets are made of thermosetting plastics.
Q) Explain the difference between thermoplastics and thermosetting plastics.
A: A plastic which can be softened repeatedly by heating and can be moulded into different shapes again and again, is called a thermoplastic.
A plastic which once set does not become soft on heating and can not be moulded a second time, is called a thermosetting plastic.
Q) Should the handle and bristles of a toothbrush be made of the same type of plastic material ? explain your answer.
A: The handle and bristles of a toothbrush can not be made of the same plastic. The handle of a toothbrush has to be hard and rigid so should be made of a thermosetting plastic where as its bristles have to be soft and flexible so should be made of thermoplastic.
Q) Explain why, plastic containers are preferred for storing food ?
A: Plastic containers are preferred for storing food due to its lower price, easy availability, light weight, good strength, durability, corrosion-resistance and chemically unreactive.
Q) Choose the thermoplastics and thermosetting plastics from the following :
Melamine, Polythene, Bakelite, Polyvinyl Chloride
A: Thermoplastics: polythene, Polyvinyl Chloride
Thermosetting plastics: Bakelite, melamine
Q) State two uses of polythene.
A: Polythene is used in making polythene bags and bottles.
Q) Write the full form of PVC. Is it thermoplastic or thermosettings plastic ?
A: Full form of PVC is Poly Vinyl Chloride. It is thermoplastic.
Q) Write two uses of bakelite.
A: Bakelite is used in making electric switch and socket.
Q) State two uses of melamine.
A: It is used to make floor tiles and dinnerwares.
Q) Give two uses of PVC.
A: It is used as an insulator on electric wires and PVC pipes for plumbing.
Q) Write some of the uses of plastics in healthcare industry.
A: disposable syringes, intravenous blood bags and heart valves are now made of plastic.
Q) Classify the following as biodegradable and non-biodegradable materials.
woollen clothes, polythene bags, paper, Aluminium Cans, Toothbrush, Peels of vegetables and fruits, cotton cloth, Jute bag, Electric switch, Frying pan handle.
A: Biodegradable : woollen clothes, paper, peels of vegetables and fruits, cotton cloth, jute bag,
Non-Biodegradable : polythene bags, aluminium cans, toothbrush, electric switch, frying pan handle.
Q) State whether plastic is biodegradable or non-biodegradable ? Give reasons for your answer.
A: Plastic is a non-biodegradable material because it is not easily decomposed by natural processes such as the action of bacteria.
Q) Explain how, the use of plastic has a bad effect on the environment.
A: The use of plastic materials affect the environment because of the following reasons:
- plastics donot decompose easily so keep on accumulating in the surroundings and pollute the environment.
- The drain water cloging by the waster plastic articles, flow over the streets and roads causing unhygienic conditions.
- Sometimes the animals eat up plastic articles with the left-over food which results their death.
- When plastic waster materials burnt, the produced poisonous gas pollute the air.
Q) Explain why, the disposal of plastic wastes is a major problem. Give two reasons only.
A: The disposal of plastic wastes is a major problem due to the following reasons :
- The articles made of plastic are non-biodegradable. They donot decompose easily.
- The burning of plastic wastes gives out harmful gases which pollute the air.
Q) What are the various ways to save the environment from excessive plastic wastes ?
A: it is not possible to stop the use of plastic, we can only take steps to minimise its use where ever possible.
- We should try to reduce the use of plastic by using other materials in their place.
- The used plastic materials should be put in the dustbin. This will keep our surrounding clean and also prevent the blockage of dirty water drains.
- Where ever possible we should reuse the plastic containers.
- Plastic wastes should be recycled.
Q) how do carelessly thrown plastic bags (polythene bags) affect :
a. dirty water drains and sewers ?
A:a. The waste plastic articles thrown here and there carelessly get into dirty water drains and sewers and clog them. This makes the dirty drain water to flow over the streets and roads causing unhygienic conditions.
b. animals (such as cows) ?
A:b. Sometimes the animals eat up the used polythene bags or plastic wrappers along with the left over food and vegetable wastes thrown on garbage dumps. The plastic wastes can choke the respiratory system of these animals or form a plastic lining in their stomach. This can cause the death of these animals.
Q) What is meant by the 3R’s principle in the context of use of plastics ?
A: The three R’s stand for: Reduce, Reuse and Recycle.
Q) State the various ways in which we can avoid ( or minimise) the use of plastics.
A: We should reduce the use of plastic articles by using articles made of other suitable materials. We should reuse plastic articles where ever possible and we should recycle old and discarded plastic articles, if possible.