Thursday, 22 April 2021

CBSE Class 8 - Chemistry - Synthetic Fibres and Plastics - Plastics Uses and Its Impact on Environment (Q and A)(#class8Science)(#eduvictors)

CBSE Class 8 - Chemistry - Synthetic Fibres and Plastics - Plastics Uses and Its Impact on Environment (Q and A)

CBSE Class 8 - Chemistry - Synthetic Fibres and Plastics - Plastics Uses and Its Impact on Environment (Q and A)(#class8Science)(#eduvictors)

Q1: What is a plastic?

Answer: Plastic is also a polymer like the synthetic fibre. All plastics do not have the same arrangement of units. In some, it is linear, whereas in others it is cross-linked.

CBSE Class 8 - Chemistry - Synthetic Fibres and Plastics - Plastics Uses and Its Impact on Environment (Q and A)(#class8Science)(#eduvictors)


Q2: What are the main properties of plastics?

Answer: 

① Plastic is easily mouldable in all types of possible shapes. 

② Most plastics are light, chemically stable and do not rust. The weight of plastic is less when compared to that of metal.

③ Some types of plastics are good insulaters and have low thermal conductivity.

④ Plastic can be recycled, coloured, reused, rolled into sheets or made into wires.

⑤ Most plastics have poor heat resistance.

⑥ Plastics have good durability (lasts longer).



Q3: Name the two main categories of plastics.

Answer: Plastic can be divided into two main types: 

– Thermoplastics and 

- Thermosetting plastics.


Q4: What are the uses of plastics?

Answer: Uses of plastic in various fields are : 

(i) Plastics find extensive use in the health-care industry. Plastics are used in making packaging of tablets, in threads used for stitching wounds, for making syringes, for making doctors’ gloves and a number of other medical instruments. 


(ii) Special plastic cookware is used in microwave ovens for cooking food without affecting the plastic vessel. 


(iii) Teflon is a special plastic on which oil and water do not stick. It is used for making non-stick coating on cook wares. 


(iv) Fire-proof plastic—Since synthetic fibre catches fire easily, uniforms of firemen have a coating of melamine plastic to make them flame resistant


(v) Due to goo durability, hardness and good electrical properties, platics are suitable for household appliances, dinnerware, writing equipment, knobs, handles, lighting fixtures, electric wire coatings etc.


(vi) Plastics like PVC, Polythenses (good rigidity) are commercially used as packaging material, making bottles and containers.


(vii) Polycarbonates are used in making machine parts, draughtsman’s and engineering instruments and electrical appratus.



Q5: What is a thermoplastic? Give examples.

Answer: A thermoplastic also called thermosoftening plastic, is a polymer that becomes pliable and mouldable above a specific temperature and returns to a solid state upon cooling.


(i) Such plastics which get easily bent or deform on heating are known as thermoplastics. Examples of thermoplastics are PVC (Poly Vinyl Chloride) and Polythene.


(ii) They have linear arrangement.


(iii) It is used in making toys, bottles, combs, containers, etc.



Q6: What is a thermosetting plastic? Give examples.

Answer: Such plastic which when moulded once, cannot be softened or deformed by heating is called thermosetting plastic. 

Examples of thermosetting plastics are Bakelite and Melamine. They have a cross linked arrangement. 


Q7: Why bakelite is used in making electrical switches?

Answer: Bakelite is thermosetting plastic. It  is a poor conductor of electricity and heat; thus, it is used for electrical switches, handles of various utensils and other electrical appliances.


Q8: What is melamine? What is its use?

Answer: Melamine is a thermosetting plastic. It is a versatile material and poor conductor of heat. It resists fire; thus, it is used in making floor tiles, kitchenware, fabrics which resist fire.


Q9: Choose the thermoplastic and thermosetting plastic from the following:

Melamine, PVC, polythene, nylon, Bakelite

Answer: 

Thermoplastic – polythene, PVC, nylon

Thermosetting plastic – bakelite, melamine



Q10: Which is better material for constructing handle of a pressure cooker -a thermoplastic or a thermosetting plastic?

Answer: The handle of the pressure cooker should not melt or get remoulded on heating. Also, the handle should be strong to hold the weight of the pressure cooker. Thermosetting plastics satisfy both of the above conditions. Hence, thermosetting plastic is the better material to construct the handle.

One of the commonly used materials for making handles is bakelite, as it is a poor conductor of heat and electricity.


Q11: Name one material used for non-stick coating on cookwares.

Answer: Teflon is one material used for non-stick coating on cookwares. Oil and water do not stick to these surfaces.


Q12: Name the monomer unit of teflon.

Answer: Teflon is a thermoplastic polymer made of chemical units called tetrafluoroethylene.


Q13:  Why plastic is lighter than metal?

Answer: Plastic and metal differ in their arrangement of molecules. Metals have a closely packed arrangement of atoms. The weight is distributed over a small space and therefore metals are heavy.

Plastic is made up of long chains of certain chemical units. They have a loosely packed arrangement. The weight is distributed over a large space in this case and therefore plastics are light in weight.


Q14: Write the uses of plastics in healthcare industry.

Answer: Plastic is used in healthcare industry in different ways:

● Gloves, masks worn by doctors are made from plastics.

● Plastic is also used to construct implants such as artificial valves, pacemakers etc.

● Plastic also plays a key role in the packaging of medicines.

● Certain medical devices which were previously made from metal components are made from plastics nowadays making them light in weight.


Q15: Why are microwave cookwares made of plastic?

Answer: Microwave cookwares are used in microwave ovens for cooking food. These microwave vessels should be able to withstand high temperatures. Special plastics are used to make the cookwares, so that food is cooked by the heat of microwave oven without affecting the plastic vessel itself.


Q16: Why should we minimise the usage of plastics?

Answer: Plastics are non-biodegradable in nature. Over usage of plastic bags can lead to accumulation of plastic waste in garbage cans. Disposal of plastic wastes is an issue. Burning plastic wastes in air would pollute the air. Disposing plastic in water endangers aquatic life and pollutes water. Since plastic is non-biodegradable, it cannot be decomposed by natural processes. Therefore, the usage of plastics should be minimised.


Q17: What are the harmful effects of plastic to our environment?

Answer: Improper disposal of plastic poses several problems. Harmful Effects of Plastic are:

① Littering of plastic in open spaces creates unhygienic conditions, as it acts as a breeding ground for insects and mosquitoes that cause diseases such as Malaria and Dengue. 


② Plastics do not undergo degradation thus, stay in the soil for many years, which affects the soil fertility and degrades the soil quality. 


③ When plastic artifacts enter the drainage and sewerage system, they block the pipes and the drains leading to waterlogging. 


④ The improperly disposed food bags, when eaten by animals, cause stomach and intestine related diseases which even lead to suffocation and death. 


⑤ Plastic items find their way to the river and other water bodies, which are then swallowed by fish, seabirds and other marine species. Thus it leads to their suffocation and death. 


⑥ The waste from the plastic manufacturing industry is thrown directly into the water bodies, thus affecting the chemical property of water and causing large scale hazard.



Q18: What are the steps we must take to protect our environment from plastic pollution?

Answer: Plastic is not environment friendly and non-biodegradable. We must take steps in order to protect our environment from plastic pollution.


1. We should never throw plastic bags or other plastic articles into water bodies, drains or on roads. 

2. We should carry cotton or jute bags for shopping. 

3. We should buy products with less plastic packaging. 

4. We should encourage people to recycle and reuse plastic.

5. We should segregate biodegradable and non-biodegradable wastes and dispose them separately.



Q19: Give examples to show that plastics are non-corrosive in nature. 

Answer: The literal meaning of non-corrosive is resistant to get destroyed by chemical action. 

Following are the examples that show that plastics are non-corrosive in nature. 

(i) Plastic containers do not react with items stored in it. 

(ii) They do not get rusted when exposed to moisture and air. 

(iii) They do not decompose when left in open for a long period.


Q20: Should the handle and bristles of a toothbrush be made of the same material? Explain your answer. 

Answer: No, the handle and bristles of a toothbrush should not be made of the same material. This is because our gums are soft and the bristles should be made of soft material so that it does not harm the gums. On the other hand, the handles should be made up of hard material so that it can give a firm grip.


👉See Also:

Ch3 - Synthetic Fibres and Plastics (Q & A) 
Ch3 - Synthetic Fibres and Plastics (MCQs)
Ch3 - Synthetic Fibres and Plastics - Know Your Plastic Bottle (RESIN Coding)
Ch3 - Synthetic Fibres and Plastics (Worksheet)


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