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ScienceClass 8ICSE

Write some of the uses of plastics in the healthcare industry.

Answer Used in packaging tablets Used in making syringes and medical instruments

ScienceClass 8ICSE

Give two uses of PVC.

Answer Polyvinyl chloride is used in clothing and furniture construction of doors and windows as well

ScienceClass 8ICSE

State two uses of melamine.

Answer It can be used to make kitchen wares It is used in fabrics that need fire resistance

ScienceClass 8ICSE

Write two uses of Bakelite.

Answer It can be used in manufacturing electrical switches and machine parts of electrical used for making the handles of a variety of

ScienceClass 8ICSE

Write the full form of PVC. Is it thermoplastic or thermosetting plastic

Answer PVC stands for Poly Vinyl Chloride. It resides under the category of thermoolastics.

ScienceClass 8ICSE

State two uses of polythene.

Answer It is a useful plastic for molding and extruding in various shapes such as bottle, sheets and pipes etc. It is used for plastic bags, stretch films because of its clear and crystalline

ScienceClass 8ICSE

Choose the thermoplastics and thermosetting plastics from the following: Melamine, Polythene, Bakelite, Polyvinyl Chloride

Answer Thermoplastics: Melamine and bakelite Thermosetting plastics: Polythene and Polyvinyl Chloride

ScienceClass 8ICSE

Explain why frying pan handles are made of thermosetting plastics.

Answer Thermosetting plastics that cannot be softened again by heating once they are moulded and they do not get affected at high temperatures. Hence, frying pan handles are made of thermosetting plastics.

ScienceClass 8ICSE

Explain why plastic containers are preferred for storing food.

Answer Plastic containers seem more convenient than metal containers. This is because of their light weight, lower price, good strength and easy handling. Being lighter as compared to metals, plastics are used in cars, aircrafts and spacecrafts also.

ScienceClass 8ICSE

Should the handle and bristles of a toothbrush be made of the same type of plastic material? Explain your answer.

Answer The handles and bristles of a toothbrush should not be made of the same type of plastic material. The handle should be made up of strong and hard plastic whereas bristles should be made up of soft ad flexible plastic.

ScienceClass 8ICSE

Explain the difference between thermoplastics and thermosetting plastics.

Answer Thermoplastic: Plastics that can be deformed easily upon heating and can be bent easily. Linear polymers and a combination of linear and cross-linked polymers come under thermoplastics. Example: PVC, nylon, polythene, etc. Thermosetting: Plastics that cannot be softened again by heating once they are moulded. Heavily cross-linked polymers come under the category of thermosetting plastics. Example: Bakelite, melamine, etc. Bakelite is used for making electrical switches whereas melamine is used for floor tiles.

ScienceClass 8ICSE

Why are thermoplastics not used for making frying panhandles?

Answer Thermoplastics that can be deformed easily upon heating and can be bent easily hence they are not used for making frying panhandles.

ScienceClass 8ICSE

Why are electric witches, plugs and sockets made of thermosetting plastics?

Answer Thermosetting plastics that cannot be softened again by heating once they are moulded. Heavily cross- linked polymers come under the category of thermosetting plastics. Example: Bakelite, melamine, etc. Bakelite is used for making electrical switches whereas melamine is used for floor tiles.

ScienceClass 8ICSE

What are plastics? Name any five commonly used articles made of plastics.

Answer Plastic is also a polymer like the synthetic fibre. Plastic is a polymer which has different types of arrangement of the monomer unit. They can have a linear structure, branched or a cross-linked structure. Articles made from plastic are: Toys, bottles, storage containers, bags, buckets.

ScienceClass 8ICSE

What are the various types of plastics? Give two examples of each type of plastics.

Answer Depending on physical properties, plastics are divided into two types: Thermoplastic and thermosetting. Thermoplastic: Plastics that can be deformed easily upon heating and can be bent Linear polymers and a combination of linear and cross-linked polymers come under thermoplastics. Example: PVC, nylon, polythene, etc. Thermosetting: Plastics that cannot be softened again by heating once they are moulded. Heavily cross-linked polymers come under the category of thermosetting plastics. Example: Bakelite, melamine, Bakelite is used for making electrical switches whereas melamine is used for floor tiles.

ScienceClass 8ICSE

Explain how, manufacturing of synthetic fibres is actually helping in the conservation of forests.

Answer The raw materials for natural fibres are mainly derived from plants and animals. It requires the cutting of a lot of trees which leads to deforestation. On the other hand, the raw materials for synthetic fibres are mainly petrochemicals such as coal. Hence, the manufacturing of synthetic fibres helps in the conservation of forests.

ScienceClass 8ICSE

What type of shirts should we buy for summer: cotton shirts or shirts made from synthetic materials (like polyester)? Give a reason for your answer.

We should buy cotton shirts for because in summer it absorbs this sweat from our body and keeps our body cool while synthetic clothes doesn't absorb the heat and make us feel hotter. The synthetic fibres melt at high temperatures during summer.

ScienceClass 8ICSE

Why should we not wear clothes made of synthetic fibres (like nylon or polyester) while working in the kitchen?

The synthetic fibres melt at high temperatures or on heating. Hence it is advised not to wear synthetic clothes while cooking or during summer.

ScienceClass 8ICSE

Write the uses of acrylic fibres.

Answer Uses of acrylic fibres: used for making sweaters used for making blankets used for making shawls used for making socks used for making carpets

ScienceClass 8ICSE

What is acrylic? State one important property of acrylic.

Answer Acrylic is flexible, light and soft, this synthetic fibre is formed using acrylic acids. These are widely used in paints, acrylic paints. Clothes made using acrylic synthetic fibre is comparatively cheaper compared to those made from natural sources like wool.

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