Class 8 Science Chapter 3 MCQ for 2020-2021
| Class: 8 | Science |
| Contents: | Multiple Choice Questions – MCQ Tests |
Class 8 Science Chapter 3 MCQ for Exams
Class 8 Science Chapter 3 MCQ with complete explanation are given below. There more than 100 questions with answers based on Class 8 Science Chapter 3 NCERT Textbook. All the 20 sets of online tests are free to use again and again. If you feel revision, please visit to Important Questions or NCERT Solutions links given just below to each question.
Q1
Paheli is writing some statements. She wants to know in which of the following statements is or are incorrect?
[A]. The fabric terry wool is obtained by mixing terylene and wool.
[B]. It is risky to wear synthetic clothes while working in the kitchen.
[C]. Some of the plastics are biodegradable.
[D]. Synthetic fibres do not melt on heating.
Answer: Option D
Explanation:When you burn synthetic fibres you find that their behaviour is different from that of the natural fibres. You must have noticed that synthetic fibres melt on heating. This is actually a disadvantage of synthetic fibres. If the clothes catch fire, it can be disastrous. The fabric melts and sticks to the body of the person wearing it. We should, therefore, not wear synthetic clothes while working in the kitchen or in a laboratory.
Q2
Which of the following statement is or are incorrect?
[A]. Polyester is a that type of fabric that do not wrinkle easily.
[B]. Teflon is used for making non-stick cookware.
[C]. Rayon is prepared by using wood pulp.
[D]. Plastic is used for making parachutes ropes.
Answer: Option D
Explanation:Nylon is another man-made fibre. In 1931, it was made without using any natural raw material (from plant or animal). Nylon is also used for making parachutes and ropes for rock climbing. A nylon thread is actually stronger than a steel wire.
Q3
Which of the following represents the correct match?
[A]. Nylon is thermosetting plastic, PVC is fibre, bakelite is thermoplastic
[B]. Nylon is fibre, PVC is thermoplastic, bakelite is thermosetting plastic
[C]. Nylon is thermosetting plastic, PVC is thermoplastic, bakelite is fibre
[D]. Nylon is fibre, PVC is thermosetting plastic, bakelite is thermoplastic
Answer: Option C
Explanation:Nylon is fibre, PVC is thermoplastic, bakelite is thermosetting plastic.
Q4
In which of the following statement is or are incorrect?
[A]. Polymer is large single chemical unit.
[B]. Acrylic is known as artificial silk.
[C]. Nylon is first fully synthetic fibre.
[D]. Polyester fibre does not wrinkle easily.
Answer: Option B
Explanation:Rayon is also known as artificial silk. Rest of all statements are correct. Hence, your answer will be option [B].
Q5
The most suitable material for the preparation of handles of cooking utensils is:
[A]. Polythene
[B]. PVC
[C]. Nylon
[D]. Bakelite
Answer: Option D
Explanation:Bakelite is used for making the handles of various cooking utensils because it is a poor conductor of heat and does not become soft on getting heated.
Q6
Consider the given statements and choose the incorrect one:
[A]. Wood pulp is a hard but wet mass of fibre obtained from wood.
[B]. Wood pulp contains a large amount of natural polymer called glucose.
[C]. Rayon is natural fibre because it is made from cellulose.
[D]. All the above.
Answer: Option D
Explanation:Wood pulp is a soft but wet mass of fibre obtained from wood. Wood pulp contains a large amount of natural polymer called “cellulose”. Rayon is man-made fibre from a natural material called cellulose (obtained from wood pulp). Nylon, polyester are fully synthetic fibres which do not require a natural material (like cellulose).
Q7
In which of the following statement is or are incorrect?
[A]. Nylon was made in the year 1931.
[B]. Nylon developed in Netherlands and London.
[C]. Nylon is not attacked by moths and ordinary chemicals.
[D]. Nylon fibre have high abrasion resistance
Answer: Option B
Explanation:The name nylon comes from the fact that it was developed in New York (NY) and London (LON).
Q8
Rayon is different from truly synthetic fibres because:
[A]. It has a silk like appearance.
[B]. It is obtained from wood pulp.
[C]. Its fibres can be woven like those of natural fibres.
[D]. It can be dyed in wide variety of colors.
Answer: Option B
Explanation:A rayon fibre was obtained by chemical treatment of wood pulp. This fibre was called rayon or artificial silk. Although rayon is obtained from a natural source, wood pulp, yet it is a man-made fibre. It is cheaper than silk and can be woven like silk fibres.
Q9
Consider the following statements and choose the correct statement(s):
[A]. PET is a very familiar form of polymer.
[B]. PET can be made into a fibre or a plastic.
[C]. PET is replacing materials like glass.
[D]. All the above.
Answer: Option D
Explanation:Here, all the statements are correct. Hence, your answer will be option [D].
Q10
Paheli is writing some statements. She wants to know in which of the following statements is or are incorrect?
[A]. The fabric terry wool is obtained by mixing terylene and wool.
[B]. It is risky to wear synthetic clothes while working in the kitchen.
[C]. Most of the plastics are biodegradable.
[D]. Synthetic fibres do not melt on heating.
Answer: Option D
Explanation:When you burn synthetic fibres you find that their behaviour is different from that of the natural fibres. You must have noticed that synthetic fibres melt on heating. This is actually a disadvantage of synthetic fibres. If the clothes catch fire, it can be disastrous. The fabric melts and sticks to the body of the person wearing it. We should, therefore, not wear synthetic clothes while working in the kitchen or in a laboratory.
Identification of fibres by burning their threads
| Cotton: | Burns completely, leaving no residue. |
| Nylon: | Burns slowly; fabric shrinks after exposure to flame, forms hard beads and gives off a smell of burning hair. |
| Wool and Silk | Burns slowly, with a smell like that of burning hair but no beads are produced. |
| Polyester | Results are like nylon, except that black smoke is produced. |
| Rayon | Burns quickly with a smell of burning paper. |
| Acrylic | Burns slowly with a sooty flame; fabric shrinks from flame, and forms black beads. |
Detergent
Leftover chemical substances obtained from petroleum products were treated with sulphuric acid to invent a new soap-like product known as detergent.
What is a polymer?
A long chain of molecules is called a polymer. It is made up of a large number of monomer molecules joined end to end to form a large molecule. There are many polymers that occur naturally, such as rubber, silk, wool and even cotton.
Which is the first man made synthetic polymer?
The first man-made synthetic fibre, nylon, was put into commercial production in 1939 by a team of scientists of the famous chemical company, E.I. Dupont de Nemours. Nylon derives its name from the first letter of ‘New York’ and first three letters of ‘London’, the two cities where it was simultaneously developed and marked.
What is Rayon?
Rayon is a type of synthetic (man-made) material that resembles silk in appearance.
What are the different forms of Terylene?
Terylene has wool-like texture, which is why it is often used to weave fabrics for making suits, trousers, etc. It is called terycot when blended with cotton, and terywool when mixed with wool.
