{"id":24774,"date":"2021-06-21T11:29:04","date_gmt":"2021-06-21T05:59:04","guid":{"rendered":"https:\/\/mcq-questions.com\/?p=24774"},"modified":"2022-03-02T10:38:11","modified_gmt":"2022-03-02T05:08:11","slug":"ncert-solutions-for-class-8-science-chapter-3","status":"publish","type":"post","link":"https:\/\/mcq-questions.com\/ncert-solutions-for-class-8-science-chapter-3\/","title":{"rendered":"NCERT Solutions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics"},"content":{"rendered":"

These NCERT Solutions for Class 8 Science<\/a> Chapter 3 Synthetic Fibres and Plastics Questions and Answers are prepared by our highly skilled subject experts to help students while preparing for their exams.<\/p>\n

Synthetic Fibres and Plastics NCERT Solutions for Class 8 Science Chapter 3<\/h2>\n

Class 8 Science Chapter 3 Synthetic Fibres and Plastics Textbook Exercise Questions and Answers<\/h3>\n

Page 41-42<\/span><\/p>\n

Question 1.
\nExplain why some fibres are called synthetic.
\nAnswer:
\nSome fibres are called synthetic fibres because they are man-made. These fibres are made by the combination of different types of chemicals in industries and their properties are also different from those of the natural fibres. Some of the examples of synthetic fibres are nylon, rayon, acrylic, polyester, etc.<\/p>\n

Question 2.
\nMark (\u2713) the correct answer. Rayon is different from synthetic fibres because
\na. it has a silk-like appearance.
\nb. it is obtained from wood pulp.
\nc. its fibres can also be woven like those of natural fibres.
\nAnswer:
\nb. it is obtained from wood pulp.<\/p>\n

Question 3.
\nFill in the blanks with appropriate words.
\na. Synthetic fibres are also called …………… or …………… fibres.
\nb. Synthetic fibres are synthesised from raw material called ……………
\nc. Like synthetic fibres, plastic is also a ……………
\nAnswer:
\na. artificial, or man-made
\nb. petrochemicals,
\nc. polymer<\/p>\n

Question 4.
\nGive examples which indicate that nylon fibres are very strong.
\nAnswer:
\nNylon is used for making parachutes. A parachute needs to be strong as it has to withstand high speed wind and huge amount of air pressure. Nylon ropes are used by mountaineers. A mountaineer\u2019s life highly depends on the strength of ropes he is using. These examples show that nylon fibres are very strong.<\/p>\n

Question 5.
\nExplain why plastic containers are favoured for storing food.
\nAnswer:
\nPlastic does not react with most of the substances. Hence, food kept in plastic container remains fresh for longer duration. Due to this, plastic containers are preferred for storing food.<\/p>\n

\"NCERT<\/p>\n

Question 6.
\nExplain the difference between thermoplastic and thermosetting plastic.
\nAnswer:<\/p>\n\n\n\n\n\n\n\n\n
Thermoplastic<\/td>\nThermosetting Plastic<\/td>\n<\/tr>\n
1. Long, straight-chained compounds.<\/td>\n1. Cross-linked compounds.<\/td>\n<\/tr>\n
2. Formed by addition polymerisation.<\/td>\n2. Formed by condensation polymerisation.<\/td>\n<\/tr>\n
3. Low strength compared to thermosetting plastics.<\/td>\n3. More strength compared to thermoplastics.<\/td>\n<\/tr>\n
4. Can be processed again and again.<\/td>\n4. Cannot be processed again or recycled.<\/td>\n<\/tr>\n
5. E.g., Polyethylene.<\/td>\n5. E.g., Bakelite, epoxy.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Question 7.
\nExplain why the following are made up of thermosetting plastics.
\na. Saucepan handles
\nb. Electric plugs\/switches\/plugboards
\nAnswer:
\na. Thermosetting plastic is fire-resistant and can withstand very high temperatures. Due to this, saucepan handles are made up of thermosetting plastic. Such handles do not heat up during cooking,<\/p>\n

b. Thermosetting plastic is a bad conductor of electricity and heat. Hence, electric plugs, switches and plugboards are made up of thermosetting plastic.<\/p>\n

Question 8.
\nCategorise the materials of the following products into \u2018can be recycled’ and \u2018cannot be recycled\u2019:
\nTelephone instruments, plastic toys, cooker handles, carry bags, ballpoint pens, plastic bowls, plastic covering on electrical wires, plastic chairs, electrical switches.
\nAnswer:<\/p>\n